Mike, the '39 and '40 have the screw-in rear window frame, and I think I read that they went to the gasket in '41 (Somebody will be along to verify that.) Don't know if a gasket would work on something designed for the separate frame. The earlier frames come up on Ebay from time to time. I got a replacement gasket from Jim Carter, which requires a joint in it. When I replaced my glass, I was happy to find the original one piece gasket was still good, so I re-used it. And, of course, glass is readily available, too. Good luck!