Installing windshield in 1939 Mercury w/ available parts

[flathead_jr]

I can not seem to find any discussion anywhere where people have had to use alternative parts to install a windshield in a 39 Mercury. Seems as there is only one manufacturer for this gasket, and the clowns refuse to do a run of these. Someone had stated that people are using the gasket from the 41 to 48 Ford and Mercury's. What process does this involve, what is different with the gasket, and what needs to be done to get it to fit nicely. I know they are not easy to install under normal circumstances, just would like to be able to do this as easily as possible. Thank you