The rear on my 74 Duster had a locking strip in the black gasket. I'm not sure if all Duster/Demon/Dart Sport cars had the same design from 70-76. I have pulled several rear windows out. I always cut the gasket apart and pulled the glass out that way. When I recently replaced the rear window in my FrankenDuster, I was careful to NOT damage the rubber seal. This was my first rear window install. ZERO leaks too.