Here is my condensed history of the 88-98 GMT400 trucks. This is a basic history of the C/K line of trucks. I posted this in the engine performance + maintenance section as there really is no other place on the forum for it... (Links: 1 2 3 4 5) Also included, is information provided by members of this forum who have responded within the pages of this history and discussion. GMT400s were introduced in April, 1987 as 1988 models. They started production in Fort Wayne, Ind., Pontiac Mich., and Oshawa, Ontario, Canada. These trucks featured large doors extending into the roofline and down almost to the bottom of the rocker. With a low step-up height and high headroom, it made for easy entry and exit. The trucks featured flush side glass, a modular-assembled bonded-flush windshield, single-piece door frames, hidden roof pillars and built-in drip rails. Trim levels included: Cheyenne: value standard full-size work truck Scottsdale: "a big step up in a sensible blend of function and form" Silverado: top of the line. Wheelbase: RCSB: 117.5 in RCLB: 131.5 in ECSB:131.5 in ECLB: 155.5 in CCLB: 159.5 in For total frame dimensions check this link: Frame Dimensions PDF Quick page reference Pg 81 RCSB C1-3500 Frame Pg 82 RCSB K1-3500 Frame Pg 83 ECSB C1-3500 Frame Pg 84 ECSB K1-3500 Frame Pg 85 ECLB C1-3500 Frame Pg 86 ECLB K1-3500 Frame Pg 87 CCLB C1-3500 Frame Pg 88 CCLB K1-3500 Frame Exterior was 3.5 in narrower than 73-87 trucks, but intrior had more leg and shoulder room and seat travel. Fleetside boxes measured 49.15in between the wheel wells and 63.8in between the side panels. At midyear, Chevy introduced a new K1500 Sportside model on the 117.5-in. wheelbase. It had a 6.5-foot sportside box with fiberglass fenders with steps built in. 2WD trucks used independent coil spring front suspension in all weight classes. 1500/2500s used a semi-floating rear axle and 3500s used a full-floating axle. 4WD had a new IFS with a hypoid driving axle and torsion bars. It utilized a wire-form design for upper control arms with lighter, stronger parts. The torsion bar springs and jounce bumpers were connected to the lower control arms. The torsion bars were computer selected to match a truck’s GVWR and balance with the rear springs. The 4x4 frame had an additional cross member under the transmission. Their new "Shift-On-The-Fly Instra-Trac" system allowed shifts from 4x2 to 4x4 high and back, without stopping, at any speed. The front axle disconnect system locked the front hubs automatically when a lever operating the 4x4 system was pulled back. The shifter connected directly to the transfer case. In 4x2 mode, the front-axle disconnect allowed the front wheels to turn freely. In 4x4 mode, the transfer case split the power equally to the front and rear wheels. The K1500 had off-road option with a front differential carrier, engine and transfer case shields, front stabilizer bar, gas shocks and heavier jounce bumpers.