Help!

[Kiwi]

Both my dad and I have have 1971 Chevrolet Cheyenne trucks with the optional sliding rear window. Both trucks have broken plastic clip/latch gizmos that lock the two pieces of glass together. I've searched repro companies (such as Classic Industries), searched auto parts stores, and searched the internet ... but to to no avail in finding a replacement clip. Thus ...

1. Does anybody know where to get a new plastic clip/latch?

2. I've seen in photos a '71-'72 sliding rear window with a metal clip/latch. Is this stock or something that someone has retrofitted to the vehicle? Anybody know where to get such a metal clip/latch?

Thanks,

John