Tell him you have a 1972 Plymouth Duster and to bring that windshield. He doesn't need the VIN. IMO if it were me and he argues, I would find a new glass guy if you have that option.
To go into more detail, the Valiant was the base model and then there were other variations of the Valiant. For example the Duster and Scamp. This goes into much more detail,
Plymouth Valiant - Wikipedia
