After looking at RichL's pictures I can see that the tracks are definitely different and the parts will not interchange. I have not seen any of the plastic ones in my cars. Most of mine are E bodies and B bodies in the 70 to 74 range. I would be curious as to when they made the change from metal to plastic and is it a blanket change or a supplier specific thing.

I have a 3D Printer and could probably print new ones but I an not sure how well they would hold up.

I would have to get my hands on one to get a few more specific dimensions but I would be willing to try.