I had a rear sliding window for my 58 Burb made at a local glass shop. I had the old one that was cracked in half to use as a pattern. It was made from "2 ply" safety glass. Cost me $65. It was a bit more than I expected but not too pricey. I'll eventually have to replace all the side glass as it is really showing it's age.

Just making the point that you can have glass fabricated if you have a useable pattern.

Thanks

Larry