Ugh, heat and UV does a great job killing plastic.
Yours is a 75 correct? Was it a late build 75, like in June or July 1975? Perhaps they started using some 76 parts already in the late 75? Clear or orange parking light lenses in the front grille? Does yours have a foot operated parking brake?
I’m not sure how I could determine the build date. The drivers door data tag has only blank spaces where the info should appear. I had a wood grain instrument bezel originally, my parking lights are clear, and I have a hand operated parking brake.