The 1988-1998 generation (officially designated GMT400) is also referred to by some enthusiasts as “OBS,” an acronym for Old Body Style. This generation brought aerodynamic designs, improved interiors, and new engines, enhancing performance and comfort. Notably, all 4th generation C/K trucks gained independent front suspension.
• 1988: The redesigned C/K line was introduced with eight distinct versions: Fleetside Single Cab, Fleetside Extended Cab, Fleetside Crew Cab, and Stepside Single Cab, each available with either 2WD (C) or 4WD (K) drivetrains. All C/K models now featured independent front suspension for improved ride. Three trim levels were offered: Cheyenne (base), Scottsdale (mid-level), and Silverado (top-tier). Engine options included a 160 hp 4.3 L V6, a 175 hp 5.0 L V8, a 210 hp 5.7 L V8, and a 6.2 L diesel V8. The ¾-ton and one-ton trucks had an additional option of a 230 hp 7.4 L V8.
• 1989: A half-ton 2WD Fleetside Sport appearance package became available, featuring black and red bumper and body trim, a black grille with a red-outlined Chevrolet emblem, chrome wheels with unique center caps, and fog lights. The 4×4 Sport appearance package was also introduced, including black bumper and body trim, wheel flares, mirrors, a sport grille, 16-inch cast-aluminum wheels, and special “4×4” badging on the box and “SPORT” badging on the tailgate, both accented by red-outlined Chevy bowties. A Z71 off-road package was also introduced, featuring skid plates and Bilstein shocks, marking the first factory off-road package offered by any of the “Big Three” automakers.
• 1990-1993: A performance-oriented model called the 454-SS was offered. It featured a 454 cubic inch V8 engine, sport suspension, quick-ratio steering, and cosmetic enhancements such as a black grille with a red Bowtie emblem.
• 1991: The 4L80-E automatic transmission became available for the ¾-ton and one-ton truck models.
• 1992: A turbo-diesel engine was added to the available powertrain options. The 4-speed manual transmission was discontinued. Stepside trucks were now available with the extended cab configuration. The Sport appearance package was discontinued after the 1992 model year due to insurance company concerns regarding high-performance trucks.
• 1993: The 700R4 automatic transmission was replaced by the electronically controlled 4L60-E automatic transmission.
• 1994: The C/K models received a mid-cycle front fascia refresh, featuring a new front grille design with a wider, beveled center bar.
• 1995: All C/K models underwent a significant mid-cycle refresh that included a redesigned interior. This new interior featured a steering wheel with a driver’s side airbag, a new dashboard with a more centrally located radio and dial-operated HVAC controls, and a revised gauge cluster. Federally mandated safety equipment, including a center high-mount stoplight (third brake light) and four-wheel anti-lock brakes (ABS), became standard. The Vortec V8 engines (likely the 5.0L and 5.7L) debuted, featuring high-flow cylinder heads, a new camshaft, roller valve lifters, and higher compression for improved power and efficiency.