Basically 67-72[maybe 73] dart stuff trim wise and doors,roof lines glass etc will interchange,same with fenders as far as body lines do line up,such as you can take a 68 dart and put on a 72 front clip and it will line up body wise but must change the whole thing as a rule of thumb,doors and such may have subtile differences such as doorlock location etc.. but will bolt on and line up,may look funny but I have seen it done,and I think if I am not mistaken that dart doors will bolt on to a demon/duster and vice versa and best if done in prs.think 73up darts were minus the wing glass in the doors like dusters...if you look up fiberglass doors for an a-body you will find that 67-73? darts and duster/demons have the same door configuration,yes grills and taillights and marker and some trim changed yr to yr but the dart was same configuration pretty much those yrs,same windshields and glass/rooflines etc...seen a 69 dart get changed to a 71 in rear section and front clip...