The 1990 model year featured a few exciting changes for the GMT400 Platform. The SS 454 package (RPO B4U) was released, combining the sport package with a host of performance upgrades including the L19 454 big block, 3.73 9.5″ rear differential, TH400 transmission, and suspension/steering upgrades. This package was only available in shortbed, regular cab pickups. 1990 also marked the first year of the new composite headlamps on certain trim levels. SUV’s were still not available in the new platform.
Here you will find specifications and information for 1990 model year Chevrolet and GMC full-size trucks.
This includes engine ratings, drivetrain specs, and chassis dimensions.
What Was New for 1990
- The B4U Sport Performance Package (Chevrolet only) for the C1500 Regular Cab 6.5 ft Fleetside: the 7.4L L19, 3-speed automatic and 3.73 axle.
- The Chevrolet BYP Sport Equipment Package now came with composite headlamps.
- The VLA Work Truck Package (Chevrolet only) for the C/K1500 8 ft Regular Cab.
- A 34 gallon fuel tank became standard on every 8 ft box model; 6.5 ft box models kept the 25 gallon tank.
- The 4.3L V6 was now offered in the 8600 lb C6P versions of the C/K2500.
- Higher 6.2L diesel ratings: 135 hp (LH6 with manual), 140 hp (LH6 with automatic) and 150 hp (LL4).
- The Z71 Off-Road Chassis Package is charted for the K1500 Extended Cab as well as the Regular Cab.
Looking for GM official tow ratings? Tow Ratings
Engines
| RPO | Engine | Power(hp) | Torque(ft-lb) | Notes |
|---|---|---|---|---|
| LB4 | 4.3L (262ci) V6 | 160 @ 4000 | 235 @ 2400 | Below 8600 GVWR |
| L03 | 5.0L (305ci) V8 | 175 @ 4000 | 270 @ 2400 | Up to 7200 GVWR |
| L05 | 5.7L (350ci) V8 | 210 @ 4000 | 300 @ 2800 | Below 8600 GVWR |
| L05 | 5.7L (350ci) V8 | 190 @ 4000 | 300 @ 2400 | 8600+ GVWR |
| L19 | 7.4L (454ci) V8 | 230 @ 3600 | 385 @ 1600 | 8600+ GVWR C1500 with B4U |
| LH6 | 6.2L (379ci) V8 Diesel | 135 @ 3600 | 240 @ 2000 | Below 8600 GVWR Manual Transmission |
| LH6 | 6.2L (379ci) V8 Diesel | 140 @ 3600 | 250 @ 2000 | Below 8600 GVWR Auto Transmission |
| LL4 | 6.2L (379ci) V8 Diesel | 150 @ 3600 | 265 @ 2000 | 8600+ GVWR |
The 4.3L was also offered at 8600 lb GVWR (C/K2500 with C6P), but the book’s rating for that version is struck through in the scan. The 7.4L in the C1500 came only with the B4U package.
Manual Transmissions
| Model | 4-SPEED SM465 | 5-SPEED W/OVERDRIVE |
|---|---|---|
| RPO | MM4 | MM5 |
| Synchronized Speeds | 2/3/4 | 1/2/3/4/5 |
| First | 6.55 | 4.02 |
| Second | 3.58 | 2.32 |
| Third | 1.70 | 1.40 |
| Fourth | 1.00 | 1.00 |
| Fifth | – | 0.73 |
| Reverse | 6.09 | 3.74 |
Automatic Transmissions
| Model | 3-SPEED TH400 | 4-SPEED w/OVERDRIVE 700R4 |
|---|---|---|
| RPO | MX1 | MX0 |
| First | 2.48 | 3.06 |
| Second | 1.48 | 1.63 |
| Third | 1.00 | 1.00 |
| Fourth | – | 0.70 |
| Reverse | 2.08 | 2.29 |
Models, Dimensions and Weights
Gasoline models at their base GVWR. Dimensions are in inches and weights in pounds. Payload is GM’s maximum payload, “based on model weight; total available for equipment and cargo.”
| Model | Cab / Box | Wheelbase | Overall Length | GVWR | Payload |
|---|---|---|---|---|---|
| C10703 | Regular, 6.5 ft Sportside | 117.5 | 194.0 | 5600 | 1420 |
| C10703 | Regular, 6.5 ft Fleetside | 117.5 | 194.1 | 5600 | 1428 |
| C10903 | Regular, 8 ft | 131.5 | 212.6 | 5600 | 1261 |
| C10753 | Extended, 6.5 ft | 141.5 | 223.0 | 6200 | 1865 |
| C10953 | Extended, 8 ft | 155.5 | 237.0 | 6200 | 1525 |
| C20903 | Regular, 8 ft | 131.5 | 212.6 | 7200 | 2694 |
| C20753 | Extended, 6.5 ft | 141.5 | 223.0 | 7200 | 2511 |
| C20953 | Extended, 8 ft | 155.5 | 237.0 | 7200 | 2418 |
| C30903 | Regular, 8 ft | 131.5 | 212.6 | 8600 | 3264 |
| C30953 | Extended, 8 ft | 155.5 | ‡ | 8600 | 3007 |
| K10703 | Regular, 6.5 ft Sportside | 117.5 | 194.0 | 5600 | 1019 |
| K10703 | Regular, 6.5 ft Fleetside | 117.5 | 194.1 | 5600 | 1027 |
| K10903 | Regular, 8 ft | 131.5 | 212.6 | 5600 | 881 |
| K10753 | Extended, 6.5 ft | 141.5 | 223.0 | 6200 | 1292 |
| K10953 | Extended, 8 ft | 155.5 | 237.0 | 6200 | 1145 |
| K20903 | Regular, 8 ft | 131.5 | 212.6 | 7200 | 2384 |
| K20753 | Extended, 6.5 ft | 141.5 | 223.0 | 7200 | 2207 |
| K20953 | Extended, 8 ft | 155.5 | 237.0 | 7200 | 2108 |
| K30903 | Regular, 8 ft | 131.5 | 212.6 | 8600 | 2906 |
| K30953 | Extended, 8 ft | 155.5 | ‡ | 8600 | 2628 |
‡ The book prints 212.6 in for the 3500 Extended Cab, the same as a Regular Cab, so the figure is left out here. The 1990 scan has no curb weight table. All boxes measure 49.1 in between the wheel wells and 19.3 in deep; the Sportside box is 49.1 in wide inside and the Fleetside 64.7 in at the floor. Front bumper to back of cab is 110.6 in on the Regular Cab and 134.6 in on the Extended Cab.
Chassis by Series
Gasoline Regular Cab models with standard equipment.
2WD (C models): independent front suspension with coil springs
| C1500 | C2500 | C3500 | |
|---|---|---|---|
| Base Engine | 4.3L V6 | 4.3L V6 | 7.4L V8 |
| Base Transmission | 5-speed manual (OD) | 5-speed manual (OD) | 4-speed manual |
| Front Axle Capacity (lb) | 2950 | 3150 | 3800 |
| Rear Axle Capacity (lb) | 3750 | 4800 | 6000 (full-floating) |
| Standard Axle Ratio | 3.08 | 3.42 | 3.42 |
| Front Rotor | 11.57″ | 11.57″ | 12.50″ |
| Rear Drum | 10″ x 2.25″ | 11.15″ x 2.75″ | 13″ x 2.5″ |
| Standard Tires | P225/75R15 | LT225/75R16D | LT245/75R16E |
| Wheels | 15″ x 6″ | 16″ x 6.5″ | 16″ x 6.5″ |
4WD (K models): independent front suspension with torsion bars, Insta-Trac hub locks
| K1500 | K2500 | K3500 | |
|---|---|---|---|
| Base Engine | 4.3L V6 | 4.3L V6 | 7.4L V8 |
| Base Transmission | 5-speed manual (OD) | 5-speed manual (OD) | 4-speed manual |
| Front Axle Capacity (lb) | 3350-3450 | 3925 | 4250 |
| Rear Axle Capacity (lb) | 3750 | 4800 | 6000 (full-floating) |
| Standard Axle Ratio | 3.42 | 3.42 | 3.42 |
| Front Rotor | 11.57″ | 11.57″ | 12.50″ |
| Rear Drum | 10″ x 2.25″ | 11.15″ x 2.75″ | 13″ x 2.5″ |
| Standard Tires | LT225/75R16C | LT225/75R16D | LT245/75R16E |
| Wheels | 16″ x 6.5″ | 16″ x 6.5″ | 16″ x 6.5″ |
The C1500 Extended Cab came standard with P235/75R15 tires on 15 x 7 wheels, and the K1500 Extended Cab with LT245/75R16C. The base engine on the 3500 Big Dooley/Heavy Hauler (R05 dual rear wheels) is the 5.7L V8. The fuel tank is 25 gallons on 6.5 ft box models and 34 gallons on 8 ft box models. Every model has variable-ratio integral power steering (16/13:1; 12.7:1 with the ZQ8 Sport Suspension) and front disc / rear drum brakes with rear-wheel anti-lock. The 10,000 lb GVWR 3500s use a hydraulic brake booster instead of a vacuum one.
GVWR Ratings
- C1500 Regular Cab: 5600 lb, or 6100 lb with the F44 Heavy-Duty Chassis (8 ft box). C1500 Extended Cab: 6200 lb.
- K1500 Regular Cab: 5600 or 6100 lb (F44). K1500 Extended Cab: 6200 or 6600 lb (F44).
- C/K1500 diesel models: 6100 lb Regular Cab; 6200 lb (C) or 6600 lb (K) Extended Cab.
- C/K2500: 7200 lb, or 8600 lb with the C6P package (4.3L, 5.7L or 6.2L diesel; not offered on the 6.5 ft Extended Cab).
- C/K3500: 8600 lb, or 10,000 lb as the Big Dooley/Heavy Hauler with R05 dual rear wheels.
Axle Ratios and RPO Codes
Rear axles in the 1990 book: the GM 3750 lb axle (8.5 in ring gear) with 2.73, 3.08, 3.42, 3.73 or 4.10; the 4800 lb axle (9.5 in) with 3.42, 3.73 or 4.10; the 6000 lb semi-floating axle (9.5 in) with 3.42 to 4.56; and the 6000 lb and 7500 lb full-floating axles (10.5 in) with 3.42 to 4.56. 4×4 front axles have an 8.25 in ring gear, or 9.25 in on the K2500 with C6P and all K3500s, which also add a 4.56 ratio. The G80 locking rear differential was optional. For axle details see the 8.5″ 10-bolt, 9.5″ 14-bolt semi-floating and 10.5″ 14-bolt full-floating articles, and use the Gearing Calculator to compare ratios.
Popular Packages
- B4U Sport Performance Package (Chevrolet only, C10703 Fleetside), the 454 SS: L19 7.4L, MX1 3-speed automatic, 3.73 rear axle, ZQ8 Sport Suspension, BYP Sport Equipment Package, high-back reclining front bucket seats with console, C60 air conditioning, G80 locking rear differential, KC4 engine oil cooler, V02 heavy-duty radiator and transmission oil cooler, TR9 auxiliary lighting, UX1 stereo, ZQ2 and ZQ3 convenience packages, A28 sliding rear window and P275/60R15 tires. Required Silverado trim and solid (ZY1) paint.
- BYP Sport Equipment Package (C/K10703): on the Chevrolet C10703, an up-level black grille, composite headlamps, body-color bumpers, fog lamps, special body side moldings, chrome 15 in wheels, black mirrors and sport decals. The K10703 version had black bumpers, black wheel flares, aluminum wheels and LT265/75R16C tires. The GMC version used a body-color grille, quad headlamps and silver bumpers, and required SLE or SLX trim with two-tone paint.
- ZQ8 Sport Suspension (C1500 only): Bilstein gas shocks and 12.7:1 ratio steering, with P275/60R15 tires.
- Z71 Off-Road Chassis Package (K1500): Bilstein shocks and NZZ skid plate, with LT265/75R16C tires.
- VLA Work Truck Package (Chevrolet only, C/K10903): 4.3L V6, 5-speed manual and front bench seat, with a dark argent metallic grille, bumper, air deflector and specific decals.
- Z81 Camper Special Chassis Equipment (2500 and 3500): DF2 camper mirrors, camper wiring harness, and a TP2 auxiliary battery on gas models.
- Z82 Heavy-Duty Trailering Special: UY7 wiring, VR4 hitch, V02 transmission oil cooler, F51 shocks and KC4 engine oil cooler (gas models). Required an automatic transmission.
- R05 Dual Rear Wheels (3500 only): the Big Dooley/Heavy Hauler, with plastic rear fender extensions and U01 roof marker lamps.
- V10 Cold-Climate Package: engine block heater, special insulation and antifreeze protection to -32 degrees.
Original Pricing
The 1990 dealer book scan doesn’t include a price list.
Source: GM’s 1990 C/K Pickup dealer data book (September 1989, revised January 1990). See the full scan on the 1990 Chevrolet Pickup Dealer Info Sheet page.
