With the third generation Rounded-Line C/R & K/V models, the Suburban became a four-door vehicle. The Rounded-Line 1970s body style remained largely unchanged for 19 model years – making this series the longest Suburban generation in production. 2WD (C/R) and 4WD models (K/V) were both available in 1/2 and 3/4 ton ("10" and "20") chassis.

Suburbans for model year 1973 now had two doors on each side (the previous generation had just one door on the driver's side), front-and-rear air conditioning, a baggage rack, a heater under the third seat and step-plates for easier access. A new Eaton Automatic Differential Lock was introduced as an option extra for the rear differential.

For the 1973 model year, the base engine was the 250 CID inline-six (100 net HP), with a 307 or 350-cubic-inch small-block V8 (115 or 155 net), or the new-for-1973 454 CID big-block V8 (240 net HP) optional. The 307 V8 was dropped for 1974, supplanted by the 305 and 400 small block V8's in 1976. The 400 was dropped after 1980, leaving the 350 as the only available engine in K-series Suburbans as the 454 was not yet offered in 4x4's. In 1982 a new 6.2 L (379 cu in) Detroit...