My mistake, I gave you info for the 66-68 windows.
I have a 1960
myself and replaced my broken windows with a material called MAKROLON, it's a plastic thats scratch resistant, won't craze or crack, yellow, it's like LEXAN. I set it in a bed of Sikaflex, then glazed the outside with Sikaflex.
I used 1/4" thick and wow what a difference, not as much heat transfer and the sound barely penetrates the plastic.