Those rubber gaskets fit a lot better, with less chance of cracking the windshield, if they're lubricated with glycerine before installing the assembly. It allows for a little slippage between the glass and the rubber as the gasket is pulled into place. A piece of thin nylon cord held into the channel that snaps over the lip on the cab with masking tape is useful also. One person holds the glass snug against the cab while someone inside pulls on the cord. The seal flips over the lip of the cab as the cord is pulled.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!