Removal and install of rear windshield 65 Barracuda

Urethane? As in a glue? That won't be fun to remove at a later date. I'd use some non-hardening "dumb-dumb" type sealer between the gasket and body. Installing the glass is not all that tough if you have a helper or two. I use plastic putty knives or bondo paddles to work the gasket lip around the glass. They're also helpful installing the lock strip.