Plexiglas side and rear windows, aluminum heads on engine, aluminum intake, aluminum case for tranny (if a 4 speed). Aluminum radiator, aluminum master cylinder, and aluminum driveshaft. Headers are often lighter than cast iron manifolds.
I think there may even be a aluminum center section for the 8 3/4 rear available.
Fiberglass rear springs, use lighter mufflers and a shorter exhaust. The list goes on-and-on!#-o