With the third generation C/K models (1973-1991), the Suburban became a 4-door vehicle. The rounded 1970s body style remained largely unchanged for 18 model years - making this series the longest in production of any Suburban. Both 2WD and 4WD models, designated "C" and "K", were offered, as well as one-half ton and three-quarter ton ("10" and "20" on the Chevy, "1500" and "2500" for GMC) models. The one ton model designation was the C or K 30 for Chevrolet and 3500 for GMC.
The base engine was the small-block 350-cubic-inch V-8. A 400-cubic-inch V-8 was optional. The 454-cubic-inch big-block V-8 was now available for the first time, most commonly in the 2WD three-quarter ton models. The 6.2 L (379 cu in) 130 hp (97 kW) Detroit Diesel V8 engine was also available from 1982-onwards. The Diesel later became the engine of choice for Suburbans exported to Europe from USA.
Three-speed Turbo-Hydramatic automatic transmissions were available for only small block engines. The Turbo-Hydramatic 400 was used for big block and 6.2 diesel engines. The 700R4 4 speed automatic was introduced in 1981 and was available with the small block and the 6.2 diesel. Towing packages, offering gearing reduction, TH400, and cooling additions for heavy loads, were available. A "positraction" limited slip differential was optional. Later vehicles came equipped with rear anti-lock brakes (available on C and K series Suburbans).
Trim options included base level, and upgraded Silverado versions. An optional 3rd row bench seat allowed for 9-passenger configurations. A rear heating system was optional, as well, to help heat the long vehicle's interior.
In 1981, automatic locking front hubs were added on four-wheel-drive models, and the NP208 transfer case replaced the NP205 in most models.
In 1986 and 1987, the method of fuel delivery for the engines was switched from carburetors to electronic fuel injection. The system that GM chose was called throttle body injection, or TBI. The change improved fuel economy, performance, and emissions. A heavy-duty four-speed automatic transmission, the 4L80-E was added in 1991.
GM temporarily changed the usual "C/K" designation to "R" and "V" for the 1987 through 1991 model years. This was done to avoid confusion with the GMT400-based Chevrolet C/K pickup trucks, which were introduced in 1988, during the overlap period.
Source: Wikipedia, 2011