GM's design engineers fashioned the "rounded-line" exterior in an effort to improve aerodynamics and fuel efficiency, using wind tunnel technology to help them sculpt the body. Third generation design traits include "double-wall" construction, sleek sculpted body work, flared secondary beltline and a aerodynamic cab which featured rounded doors cutting high into the roof and steeply raked windshield featuring an available hidden radio antenna embedded into the glass.
There were two types of pickup boxes to choose from. The first type, called "Fleetside" by Chevrolet and "Wideside" by GMC, was a "double-wall" constructed full width pickup box and featured a flared secondary beltline to complement the cab in addition to new wraparound tail lamps. Both steel and wood floors were available. The second type, called "Stepside" by Chevrolet and "Fenderside" by GMC, was a narrow width pickup box featuring steps and exposed fenders with standalone tail lamps. Initially, only wood floors were available.
The wheelbase length was extended to 117.5 in (2985 mm) for the short wheelbase pickups, and 131.5 in (3340 mm) for the long wheelbase pickups.
The rounded-line generation ultimately ran for a lengthy 15 model years (1973–1987) with the exception of the Crew-Cab, Blazer, Jimmy, and Suburban versions, which continued up until the 1991 model year.