[rgunlock]

Old thread, but it helped me out so thanks LockDoc!

On my 71, I used this method to remove both rear window and windshield without cutting the gaskets. My gaskets were pretty pliable (likely not original to the truck). I had an old Craftsman wet/dry vac I was tossing and cut the round power cord from it. Forced that behind the gasket from inside across the top and down the sides. You can actually force it far enough to go between the gasket and the top of the pinch weld lip, which holds the inside of the gasket away from the inside cab sheetmetal.

From there it was just a little persuasion with the flat of my hand to get an upper corner moving out. Might have to use your fingers right in the top corner of the gasket to help it start while pushing the glass with your other hand. After that, easy to get the rest of the top loose.