Chevrolet C/K

Medium-duty trucks were:

• 1½-ton Chevrolet C40 / GMC 3000 (1960–62), with the light-duty cab;
• Chevrolet C50 and C60;
• GMC 3500, 4000 and 5000.

Heavy-duty trucks were:

• Chevrolet C60-H[7] (a C60 with a heavier GVWR: 22,000 lbs instead of 19,500 lbs), C70 (1960–61) and C80;
• Chevrolet tandem rear axle models M60 (1963–66), M70 (1960–61) and M80 (1962–66);
• GMC 5500, 6000 and 6500;
• GMC tandem rear axle models W5000, W5500 and W6500.

• 
  1960-61 GMC medium-duty truck
• 
  1963 Chevrolet medium-/heavy-duty truck
• 
  1966 GMC medium-duty truck
• 
  1966 Chevrolet C60

A 10, 20, or 30 on the emblem indicates ​¹⁄₂-, ​³⁄₄-, or 1-ton trucks. There are also 40- to 80-series medium- and heavy-duty trucks:

• medium-duty
  • ​1 ¹⁄₂-ton C40;
  • "light" 2-ton C50;
  • 2-ton C60;
• heavy-duty
  • "light" ​2 ¹⁄₂-ton C70;
  • ​2 ¹⁄₂-ton C80.[13]

These models share the cabin of the light-duty models but sit on a taller chassis and have a taller front end of a different design, with a clamshell hood.

1500, 2500, and 3500 designations were used to indicate ​¹⁄₂-, ​³⁄₄- and 1-ton trucks. Sierra and Sierra Grande had been used as names on option packages since the 1969 model year.

In both series, the 'Highlander package' included special color-coordinated houndstooth cloth inserts and additional trim colors and insulation.

The third-generation pickups were offered in several equipment level packages or trim packages. Chevrolet/GMC used various names for the trim levels throughout the vehicle's life cycle and some were rearranged in their class order. For the 1973 and 1974 model years, the base (standard) trim level was Custom/Custom, mid-range trims were Custom Deluxe/Super Custom, luxury trims were Cheyenne/Sierra, and top-of-the-line luxury trim levels were Cheyenne Super/Sierra Grande.[16]

For the 1975 model year the trim levels were revised and the base trims were now Custom Deluxe/Sierra, mid-range trims were Scottsdale/Sierra Grande, luxury trims were Cheyenne/High Sierra, and the top-of-the-line luxury trim levels were now known as Silverado/Sierra Classic. They remained in this configuration up to the 1987 model year.[25] For the 1982 model year, the luxury trim levels were dropped, leaving the base, midrange, and top-of-the-line luxury trim level packages.[28]

Soft touch materials were used throughout the passenger cabin, such as the dashboard, doors (arm rests), steering wheel, and shift levers. Subtle grained interior panels and bright metal work was used on the inside with high-quality materials also used on the outside, like chrome, aluminium, and polished stainless steel, particularly on top-of-the-line luxury Silverado or Sierra Classic trim levels. Custom Vinyl vinyl or soft Custom Cloth cloth and velour seating surfaces were used along with fabric headliners, door inserts, and plush carpeting, depending on the trim level. Upper class trim levels also used acoustic deadening materials for quieter ride comfort.[29] From model years 1973 to 1977, chestnut wood grain inserts were used on the dashboard and doors for further visual enhancement. The wood grain inserts were replaced by bright brushed aluminium inserts for model years 1978 to 1987.[30] A Delco AM/FM audio sound system and an all-season climate control system that heated, cooled, cleaned, and dehumidified were optional extras.[31]

At its launch in 1972, the Square-body C/K-Series introduced two firsts in safety advancements concerning full-size pickups, and would later lead a third safety advancement in 1975. The first was the standard passenger-side sideview mirror, and the second was the energy-absorbing collapsible steering column. Patented by GM and already in use in its cars since 1967, the new energy-absorbing steering column was standard on all C-Series and K-Series models.[16][32][33]

The third safety advancement was the introduction of dual front lap-and-shoulder safety belts with emergency locking retractors for outboard occupants in 1975 for the 1976 model year.[34] These replaced the outdated and inadequate lap belts previously used. A center lap safety belt with slack adjustment was provided for the center occupant. Ford and Dodge would follow one model year later adding lap-and-shoulder safety belts to their pickups.[35][36]

Other safety features included soft-padded interior panels for appearance and safety, 3,329 square inches of tempered and laminated safety glass, prismatic rearview mirror, six turn-signal indicator lamps with asymmetrical flash, four-way hazard function, and lane departure function.[16][29][37][38]

1983 Chevrolet C-10 Custom Deluxe

Third-generation Square-body C/K-Series pickups gained an all-new, high tensile strength carbon steel ladder type frame with "drop center" design.[23][39][40] Steering controls included variable-ratio recirculating ball steering gear with optional hydraulic power assist. Braking controls included front self-adjusting disc brakes with rear finned drum brakes and optional four-wheel hydraulic Hydra-Boost or Vacuum-Boost power assist.[16] Engines choices initially consisted of six or eight cylinder engines with either manual or Turbo Hydra-Matic transmissions.[16]

C-Series pickups included two-wheel drive and featured an independent front suspension (IFS) system with contoured lower control "A" arms and coil springs. GM's new Load Control rear suspension system took up residence in the back. The Load Control rear suspension system consisted of a rear live axle with dual stage Vari-Rate multi-leaf springs and asymmetrical (offset) shock absorber geometry, to help sort out any "wheel hop" under heavy loads or hard acceleration.[23]

K-Series pickups included either Conventional, Permanent, or Shift-on-the-move four-wheel drive. The latter system was introduced for 1981. Regardless of the type of four-wheel drive system equipped, all K-Series pickups featured four-corner Vari-Rate multi-leaf springs, front live axle with symmetrical (inline) shock absorber geometry, and the Load Control rear suspension system. K-Series pickups also featured an off-road oriented design, with the transfer case bolted directly to the transmission and running gear tucked up as high as possible under the vehicle to reduce the chances of snagging vital components on obstacles, as well as to achieve a low silhouette and optimal ground clearance.[41] Exposed brake lines wrapped in steel were standard, with underbody skid plate armor optional for further protection.

Conventional four-wheel drive pickups featured manual locking hubs and a two-speed New Process 205 transfer case with four drive modes: Two High, Four High, Neutral, and Four Low. Two High gave a 0:100 torque split, while Four High yielded a locked 50:50 torque split. Four Low applied reduction gearing. The front and rear propeller shafts were locked at all times in Four High and Four Low. Neutral allowed for flat towing, or use of the power take off (PTO).[42]

Full-time four-wheel drive pickups featured a two-speed New Process 203 transfer case with center differential and lock. Five positions were provided: High Loc, High, Neutral, Low, and Low Loc. In High the center differential was unlocked and allowed the front and rear propeller shafts to slip as needed for full-time operation. The system could be manually shifted into High Loc which locked the center differential for a locked 50:50 torque split. Low and Low Loc applied reduction gearing with or without lock, depending on the mode selected. Neutral was also available for use of the PTO.[42]

A new Eaton Automatic Differential Lock (ADL) was introduced in 1973 as an optional extra on the Rounded-Line C/K-Series pickups, for the rear hypoid differential. The new automatic locking differential was offered under the G86 code, replacing the Eaton NoSpin differential, and eventually replacing the old Positraction limited-slip differential in 1974, at which point it assumed the G80 code.[43] The Eaton ADL featured intelligent differential control via an internal governor which monitored vehicle speed and wheel slip to know when to automatically lock and could lockup 100 percent at or below 20 mph (32 km/h) increasing tractive effort. The differential lock would unlock and deactivate at speeds above 20 mph for safety reasons, such as the vehicle being on dry pavement.[44]

Towing and payload capacity ratings for Rounded-Line C/K-Series pickups varied, depending on how they were configured. Factors such as engine and transmission combination, differential gear ratio, curb weight, and whether the pickup was two-wheel drive or four-wheel drive decided how much the pickup could safely tow or haul.

A properly equipped C-Series half-ton class pickup could tow up to 8,000 lbs (4 tons) of braked trailer, while a properly equipped C-Series three quarter-ton or one-ton class pickup could tow up to 12,000 lbs (6 tons) of braked trailer.[45] Adding four-wheel drive reduced towing capability due to increased curb weight, which resulted from additional driveline components (transfer case, front axle, front differential, front propeller shaft, and so on) needed to facilitate four-wheel drive. A properly equipped K-Series half-ton or three quarter-ton class pickup could tow up to 6,500 lbs (3.25 tons) of braked trailer, whilst a properly equipped K-Series one-ton class pickup could tow 500 lbs more, up to 7,000 lbs (3.5 tons) of braked trailer.[45]

Heavy-duty towing equipment was available for both C and K-Series pickups, such as the Trailering Special package (included power steering, uprated battery, and uprated generator), 7-pin trailer electrics connector, heavy-duty engine oil cooler, heavy-duty transmission oil cooler, and a weight distributing trailer hitch.[25][46]

For the 1975 model year, the 185 hp 400 cu in (6.6 L) small-block V-8 was added to the line and there was a realignment of Chevy trim levels, along with new grilles and clear/white instead of orange front turn signals. Base models gained a passenger-side woodgrain dash accent and a new plaid upholstery pattern (which would change slightly each year until 1978).

A new gauge to show voltage replaced the ammeter in 1976, and the engine size decals were removed from the grille during this model year.

For 1977 models, power windows and power door locks were introduced as an optional extra. There was another round of new grilles, revised inner door panels that left less metal exposed, a four-wheel drive, full one-ton chassis was added to the lineup, and a Dana 60 was used for the front axle, as well as an electric oil pressure gauge replacing the mechanical unit. Trucks with an optional trim level, but without an additional wheel upgrade, received flatter stainless steel hubcaps, still with painted accents. This was also the only year with yellow painted trim instead of black.

All 1978 models got new, flatter dash trim panels, black on the lower two trims and aluminum-look on the fancier two. Base models received the flatter stainless hubcaps. The gas tank was moved from the right side to the left, and stepsides got new squared-off taillights with built-in backup lights and side markers, while the rear fenders were smoothed out where the old side markers were. Fuel doors were added on models equipped with a bed to hide the previously exposed fuel caps.

The 1979 models got a new grille surround that incorporated the turn signals; inside there was a new full-width "houndstooth" seat trim on base models and a (rare) fifth interior color option on the higher series called "oyster" by Chevrolet and "Mystic" by GMC (mostly white with a gray dash, carpeting and cloth). Fuel doors were added in 79 to the rest of the lineup, following the previous years change on models with a bed.

For the 1980 model year, full-time four-wheel drive was discontinued on K-Series, leaving only conventional four-wheel drive. Some pickups gained a new grille, others did not; high-trim Chevys had both a new surround that incorporated near-flush square headlights and revised turn signals with a new, squarer grille pattern, while a GMC base model was entirely carryover, base Chevys had the new center section in the 1979 surround while GMCs with uplevel trims or the separate RPO V22 option had the new square-light surround with the main grille introduced in 1977. Blue interiors were a darker shade than before.

[47]

A mid-life cycle cosmetic facelift and mechanical refresh was carried out for the 1981 model year. In response to the recent 1979 energy crisis, the 1981 rework featured several fuel saving techniques to help make the Rounded-Line C/K-Series pickups more fuel efficient. Again, engineers turned to wind tunnels to resculpt the front end with new sheet metal, reducing areas which could hinder air flow and cause drag.[29][48] A sleeker front bow-like look emerged, similar to a ship's bow with the front end being gently swept back from the center. New dual tier halogen headlamps became available with the Deluxe Front Appearance package.[29] Mechanical updates included more anti-corrosion techniques, reduced weight, and a new 5.0 L 305 cubic inch V-8 with electronic spark control. The 5.7 L 350 cubic inch pushrod V-8 was offered in California in place of the new 5.0 L 305 engine with electronic spark control, which did not meet California's emissions requirements.[29]

A new Shift-on-the-move four-wheel drive system with two-speed dual range New Process 208 aluminium transfer case was introduced on K-Series pickups for the 1981 model year. It replaced the permanent four-wheel drive system, on pre-1980 models. The shift-on-the-move four-wheel drive system featured new automatic self locking hubs and synchronized direct high range planetary gearing, such that the truck could be shifted from two-wheel drive, to fully locked four-wheel drive at speeds of up to 25 mph.[49] Once the shift from two-wheel drive to four-wheel drive was made, the vehicle could be driven at any forward or reverse speed. Four drive modes were offered: Two High, Four High, Neutral, and Four Low. Two High gave a 0:100 torque split, with Four High yielding a locked 50:50 torque split through direct synchronized gearing. Four Low applied reduction gearing with a 2.61:1 ratio, compared to the previous New Process 205's 1.96:1. The front and rear propeller shafts were locked at all times in Four High and Four Low. Neutral was provided for disengagement of both propeller shafts. Conventional four-wheel drive was still available with manual locking hubs.

A new four-speed Turbo Hydra-Matic 700R4 transmission with overdrive gearing became available in 1981 for the 1982 model year. The 151 hp 379 cu in (6.2 L) Detroit Diesel V-8 was added[50] to replace the LF9 Oldsmobile diesel that had been optional on 1/2-ton 2WD models since 1978. Chrome front bumpers were now standard on base models.

1985 saw the new 262 cu in (4.3 L) LB1 (with a Rochester Quadrajet carburetor in lieu of fuel injection) introduced to replace the 250 inline six (the 292 continued in production until it was officially phased out in 1990). Hydraulic clutches were introduced. Also, a new grill was used.[51] The most expensive radio was the AM/FM stereo seek/scan with cassette tape at $594.[51] A variation of the C/K series was introduced in 1985 in Brazil,[52] replacing the locally produced C10, introduced in 1964.

For the 1987 model year, the last model year for the conventional cab pickups, the Rounded-Line C/K-Series were renamed the R/V-Series. R-Series now designated two-wheel drive, while V-Series represented four-wheel drive.[53] The name change is also found in the vehicle identification number.[54] This was done in preparation for the next generation GMT400 trucks, which were produced concurrently with the older line. The new 1988 model trucks entered production December 8, 1986 at Pontiac East, Oshawa, and the new Fort Wayne plant. The 1987 models continued to be built at Janesville, St. Louis, and Flint.[55]

Along with the name change, came other major improvements and tweaks for the final model year of the conventional cab pickups. Single-point electronic throttle-body fuel injection (TBI) was introduced on GM's full-size pickups, with new electric fuel pumps and high-pressure fuel lines. In addition, a "smart" powertrain control module (PCM) was also introduced, which controlled the fuel injection system, fuel-to-air burn ratio, engine ignition timing, and (if equipped with an automatic transmission) the Turbo Hydra-Matic's turbine torque converter clutch.[56] The 5.7 L 350 cubic inch pushrod V-8 was introduced to the order books for R-Series and V-Series half-ton class pickups, with the new TBI fuel injection system. Horsepower and torque output was increased to 210 hp, and 300 lb-ft of torque.[57]

After 1987, R/V remained in use for the Rounded-Line one-ton crew cab pickups through 1991 (built at Janesville), chassis cab (which was phased out after 1989; single cabs were discontinued in the US/Canada where the production tooling was shipped to Mexico where it remained in production until 1991), and the Rounded-Line utilities (Chevrolet K5 Blazer and Suburban, built at Flint) through 1991. From the 1988 model year and onward, C/K was re-used for the fourth-generation "GMT400" design.[58]

• 
  1979 GMC K15 Sierra Grande Regular Cab Short Bed Stepside
• 
  1975-1976 Chevrolet C/K
• 
  1975-1976 GMC C/K
• 
  1981-1982 Chevrolet C30 Silverado 3+3 Double Cab conversion
• 
  GMC Medium-Duty conventional, predecessor to the Topkick
• 
  1976 Chevrolet K20 Silverado Regular Cab Long Bed Camper Special

The third generation of GM's full-size pickup line had a fuel tank design that drew criticism after the model run ended. The fuel tank was relocated from the cab to the outboard sides of one or both frame rails beneath the cab floor extending under the leading edge of the pickup box, commonly referred to as a sidesaddle arrangement.

The writer and editorialist Walter Olson made the following points: According to a later-debunked 1993 report on Dateline NBC, this arrangement made the trucks prone to exploding in a side collision.[59] The faked video was staged by an expert witness for hire against GM, Bruce Enz of The Institute for Safety Analysis. Enz used incendiary devices and a poorly fitted gas cap to create the impression of a dangerous vehicle.[60] Regardless of any increased risk of fire, the GM trucks had safety records in side-impact crashes statistically indistinguishable from their Ford and Dodge counterparts. The sidesaddle fuel tanks themselves, were found to have a robust design highly resistant to crushing or crumpling from a side impact. Trucks equipped with these tanks met and exceeded the requirements of Federal Motor Vehicle Safety Standard No. 301. Studies showed that it would take about 4,000 side-impact crashes with such a truck to get one with fire, major injury, or fatality.[61]

It was also found that the Dateline report was dishonest about the fuel tanks rupturing and the alleged 30 mph (48 km/h) speed at which the collision was conducted. The actual speed was found to be higher, around 40 mph (64 km/h), and after x-ray examination of the fuel tanks from the C/K pickups used in the staged collision, it was discovered they had not ruptured and were intact.[62][63]

Fatality figures vary wildly. A study by Failure Analysis Associates (now Exponent, Inc.) found 155 fatalities in these GM trucks between 1972 and 1989 involving both side impact and fire.[64] The Center for Auto Safety, Ralph Nader's lobbying group, claims "over 1,800 fatalities" between 1973 and 2000 involving both side impact and fire.[65]

In 1993 the bad publicity generated by the Dateline story spawned several class action lawsuits. In addition GM was sued more than 100 times in lawsuits brought by individuals who were burned in GM trucks.[66] Nearly all of those cases were settled out of court. In 1993, a Georgia jury awarded more than $105 million, including $101 million in punitive damages, to the parents of a 17 year old named Shannon Moseley who burned to death.[66] The verdict was later overturned by an appeals court[67] and the case settled before it could be re-tried.

On October 17, 1994, U.S. Transportation Secretary Federico F. Pena announced that a two-year investigation had found that the trucks posed a fire hazard. Federal officials estimated that 150 persons may have died in preventable fiery crashes. The gas tanks leaked in at least two crash tests performed by GM around the time the trucks were first sold in 1972. The federal report also stated that 50 MPH crash tests performed in the early 1980s "clearly demonstrated" the tanks were susceptible to puncturing. Perhaps influencing the government's decision on whether or not to order a recall is the fact that in the 1980s GM prevailed in court when the federal government ordered a recall over a suspected brake problem. GM and other auto companies were required to meet the National Traffic and Motor Vehicle Safety Act, which requires that they not only meet standards but produce vehicles which operate safely under real conditions.[68]

GM also settled with the U.S. National Highway Traffic Safety Administration (NHTSA) in 1994 for the amount of $51 million to be used for safety programs. GM also offered owners $1000 coupons toward the purchase of a new truck with a trade-in of the old one.[67] The fourth-generation C/K-Series pickups of 1988–2001, designed and produced well before the lawsuits, had a new single fuel tank located within the frame rails.

Sevel Argentina S.A. built the Chevrolet C10 in its Córdoba plant from 1985 to 1991. The gasoline version used the Chevy 250 CID engine (4,093 cc) familiar to most Latin American markets, producing 130 hp. Because of Sevel being a subsidiary of Peugeot, the C10 was also available with a 70 hp Indénor XD2 2,304 cc diesel engine, perhaps best known in the US from the Peugeot 504.

For 1999, while the Chevrolet Silverado 1500 was all-new, its predecessor, the C/K 1500, was sold alongside the all-new model. Only available in Silverado trim with the two or three-door Extended Cab configuration, the 1999 C/K 1500 included more standard equipment over the 1998 models, such as air conditioning, premium cloth seating surfaces with power lumbar support for both front seats, and the 5.0 L Vortec V8 gasoline engine as standard equipment with the option of the 5.7 L Vortec V8 gasoline engine, both with a four-speed automatic transmission (the manual transmission, gasoline V6 and diesel V8 engine options were discontinued for 1999 half-ton models). Those wanting a Regular Cab or less-expensive, lesser-equipped trucks (especially those with a gasoline V6 engine or manual transmission) would now need to opt for the all-new 1999 Chevrolet Silverado 1500.

Holden imported the GMC C/K beginning in 1996, exclusively for ambulance use. Unlike their Holden Suburban siblings, they were not sold to the general public nor did they bear Holden badging,[72] and they were not built as right-hand-drive at the factory.

Jacab Ambulance in Tamworth purchased the GMCs and converted them to ambulances, and also handled the RHD conversion.

In 1989, a Sport Equipment Package was available on either C/K1500 fleetside short-bed single cab models with the YE9 silverado interior trim package. The Sport Equipment Package featured a black grille with a red outlined bow-tie emblem, black moldings outlined in red, body color front and rear bumpers, black mirrors and "SPORT" identification decals on the box and on the tailgate.

-2WD only models also received a black air dam with integrated fog lamps and chrome 15X7 wheels with specialized chromed plastic center caps.

-4WD only models were exclusively white or black and also received black wheel flares, black tow hooks, black bumpers without impact strip, 16–inch cast-aluminum wheels and additional 4x4 sport decals on the fleet side box with “SPORT” on the tailgate.

The BYP package was only available on trucks painted in solid red, black, and white in 1989. It has been reported that the 89 sport was a limited production run set to determine how well the package would be received by consumers in the years to follow. There were no suspension or engine upgrades provided with any of the sport packages as this was an appearance only option. Suspension or any other upgrades or options are only determined by additional RPO codes. Early 1989 models were sold with Factory Optioned Bilstein Shocks if the RPO code was applied. It has been rumored that only 5,400 BYP packaged trucks may have been produced in 1989.

In 1990, the Sport was introduced and carried on until 1992 when sales began to fall off. In 1993 General Motors, not willing to let this style package become a thing of the past Re-introduced the Sport branded trucks along with the 454SS. GMC models could now be optioned with a Sport appearance package with their own unique decals that were a different script than the original Sport decals that came on the 1989 to 1992 models. As of 1993 the new models were optioned with solid exterior mirrors low-profile aerodynamic manual units color matched to the body color. A ZQ8 Sport suspension package was now an available option for 2WD models which still included Bilstein Shocks, 12:7:1 ratio steering and 275/60R15 tires. The Sport Equipment Package is the most frequently faked / cloned for the Chevrolet trucks but RPO decoding will reveal if it is a true "sport" or not.

• 
  1989 Chevrolet Silverado Sport
• 
  Factory original Chevrolet Silverado sport truck in Tennessee

In 1990, Chevrolet introduced a high-performance variant of the GMT400 under the Super Sport emblem called the 454 SS. It was available only as a 2WD half-ton regular cab short box in Onyx Black only with a garnet red interior. The 454SS was powered by a 454 cu in (7.4 L) V8 producing 230 hp (172 kW) and 385 lb⋅ft (522 N⋅m).[75] A 3-speed automatic transmission (Turbo Hydra-Matic 400) and 3.73 rear axle ratio added to the truck's performance. The axle itself is unique, being a 14-bolt semi-floating unit which uses standard Chevrolet 5 on 5-inch wheels—the only factory-produced 14-bolt axle with such a wheel bolt pattern. The suspension was also upgraded with 32 mm (1.3 in) Bilstein gas-filled shock absorbers, a 32 mm (1.3 in) front stabilizer bar, and 12.7:1 fast-ratio steering gear assembly.

Unique exterior features included a front air dam with fog lights, special rims, decals displaying "454SS" on the bed sides, red trim emblems, and black painted grille, bumpers, and mirrors. The interior was also unique with a special plush Garnet Red cloth with black trim, high-back reclining sport bucket seats, and center console.

For 1991, a four-speed electronic automatic transmission (known as the 4L80E), 25 more horsepower, and even higher torque (405 lbs/ft at 2400 rpm) were added to the 454 SS. The rear-axle ratio was also lowered to 4.10:1 for extra jolt off the line. On the dash was a tachometer, oddly omitted from 1990 models. Dual exhaust was also added during the '93 model year.

The MSRP of the 1990 model was US$18,295 with a $550 destination charge. A total of 16,953 units were sold over the 4 years the 454 SS was in production, with 1990, the first year of production, selling 13,748 units alone. The 454 SS was discontinued after the 1993 model year.

• 
  Chevrolet 454 SS

1997-2002 GMC 3500HD Cab and Chassis with Dump Body

In 1991, GM introduced a 15,000 pound GVWR C3500 HD model under both the Chevrolet and GMC nameplates. It was positioned to bridge the gap between light-duty and medium-duty trucks. It was only offered as a standard chassis cab until 1996 when a crew chassis cab was also offered. It is not clear if the crew cab was for fleet orders only, or if it was available to the general public. An extended cab was never offered, though such conversions have been done. All paint colors and most options were offered in the C3500 HD. Upper cab marker/clearance lights were not optional equipment on the C3500HD. The two mirror options are the camper style and west coast style mirrors.

The common drive axle used on the C3500 HD was the Dana 80, an 85.8-inch-wide full floating axle with an 11-inch ring gear fitted with 19.5–inch x 6.0 wheels. The front axle was a solid I-beam drop axle, similar to the axles of medium and heavy duty trucks. Both front and rear leaf sprung axles had disc brakes.

Available wheelbases were 135.5, 159.5, and 183.5 inches (3442, 4051, and 4661 mm). The C3500 HD used a different frame than the C/K3500 cab and chassis. The C/K3500 cab and chassis and C3500 HD rear frame rails are spaced at industry standard 34 inches for easy fitment of bodies but that is where the similarity ends. The HD frame is much heavier and exits straight out behind the high mounted cab necessitating the unmistakable HD filler panel between the bumper and grille. The front fenders were also equipped with the same flares used on 4x4 models of the lighter trucks to cover the increased track width and larger tires.

Two transmissions were offered in the C3500 HD; the 4L80E 4-speed OD automatic, and the NV4500 5-speed manual.

There were also Brazilian versions of the C3500 HD, offered in the domestic market only as a GMC and in regional export markets (basically Argentina and Uruguay) as Chevrolet. These versions were badged in a different way than its American counterparts, as 6-100 and 6-150 according to their approximated GVWR in metric tonnes (a little above 6 tonnes) and the power in PS (100PS for the 4-cylinder version fitted with a Maxion S4 engine and 150PS fitted with the MWM Sprint 6.07TC), always bolted to a 5-speed manual. A version of the short-bed C2500 used the GMC 3500 HD nameplate only between 2000 and 2001 and fitted with the MWM engine, as it had the GVWR increased to 3500 kilograms in order to be classified as a truck in Brazil to attract lower taxes and annual licensing fees.

GM never offered a four-wheel-drive K3500 HD counterpart of the C3500 HD. Several aftermarket conversion companies offered a 4x4 version with either a Dana 60 or Dana 70 front axle. At least one company, Monroe Truck, was offered by GM dealers as a ship-through 4WD upfit using the RPO code VCB. Tulsa is another company that did 4x4 conversions for utility companies. Quigley conversions were mostly for fire/ambulance applications.

Engine offerings for the C3500 HD included three gasoline engines; from 1991 to 1995 5.7L 350 Small Block and 7.4L GEN V Big Block. In 1996 both the 5.7 and GEN V 7.4 were replaced by the new Gen VI 7.4L Vortec Big Block.

One of the main additions to the 1991–2000 years is that it introduced the 305 cu in a traditional 5.0L V8 and also in a 5.7L V8 which was most common in the SLE packages.

The RPO L65 6.5L Turbo Diesel debuted in the C3500 HD in 1991, the year of the engine's release. The 6.5 was the only diesel engine offered for the entire production run of the T400 C3500 HD. No diesel was available for 1991, the first C3500 HD production year.

While all other C/K pickup models were dropped by 2000, the C3500 HD was produced until 2002 due to fleet demand. In the brochures it is referred to as Sierra Classic/Silverado Classic. There were two engine choices: the 8.1 L Vortec V8 replaced the Gen VI 7.4 L Vortec, while the venerable 6.5 L Turbo Diesel continued.

GMT400 Trucks were sold with 15 inch wheels on C1500 models, 16 wheels on all other models, except the C3500 HD which had 19.5 inch wheels.

Bolt patterns for the wheels are:

C1500 - 5 x 5" K1500, CK2500 Light Duty - 6 x 5.5" CK2500 HD, CK3500 - 8 x 6.5" C3500 HD - 10 x 7.25"

Hollander 1366 - steel 19.5 x 6 inch, 10 lug, dually wheel, C3500 HD only

Hollander 1618 - cast aluminum 16 x 7 inch wheel, 6 lug K1500 "4x4" wheel

Hollander 1619 - steel 16 x 6.5 8 lug CK2500HD, CK3500 Non-dually wheel

Hollander 1621 - steel 16 x 6.5 inch 6 lug wheel, 2400 pound rating at 80 psi

Hollander 1622A - steel 16 x 6.5 inch 6 lug wheel, 1550 pound rating at 55 psi

Hollander 1622B - steel 16 x 6.5 inch 6 lug wheel, 2400 pound rating at 80 psi

Hollander 1670A - chrome steel 15 x 7 inch 5 lug wheel offered on 454SS C1500 model

Hollander 1670B - painted steel 15 x 7 inch 5 lug wheel, spare for 454SS

Hollander 1740 - Cast aluminum 15 x 7 inch 5 lug wheel offered on 1988-1992 C1500 models in very limited numbers

Alcoa XXXX 16 x 7 inch 6 lug forged aluminum wheel - used on 2000 Tahoe Z71

Ronal R36 - 16 x 7 inch cast aluminum 5 spoke, 5 lug wheel, 2000 Tahoe Limited