70-71 dusters are light too. No heavy fastback rear window and no rear 1/4 window mechanisms. Lightweight simple plastic grille. No nosecone, no front or rear valence.
67-69 valiants too of course.
But lightest abody is 60-62 valiant 2 door post. Just super tight engine campartment, two year front suspension, tight rear tire room....and the looks are an "aquired taste"