Body construction consisted of a rigid frame made of welded aluminum extrusions. The body frame was mounted on the chassis steel ladder frame using body isolators. The floor was marine plywood, except where it sloped up at the extremities, where they were plate aluminum. The body panels are fiber reinforced plastic (fiberglass) below the waistline frame extrusion and at the ends. The upper side body and roof panels between the ends are sheet aluminum. GMCs are notable for their large expanse of windows, which redefined the RV industry at the time. They often had luxury features common on upper models of GM brands, such as cruise control, air conditioning, AM/FM/8-track sound systems, an aluminum/fiberglass body, as well as air suspension.