I believe 1970 Dart was the only one that got fiberglass extensions, they had the mounting studs screw in kinda like the hood scoops on some years. 1971 were made of metal with the mounting studs cast in, 1972 was similar but the inside area where the eyebrow trim goes is more shallow, not a big deal if you don’t have the trim. Some may have a single hole on the side if the car was equipped with the aluminum side trim moulding.
They all interchange, just pointing out the differences if you want to be correct. They can all be hard to find in good shape....fiberglass ones crack and break, the metal ones often have the mounting studs break off.
