Duster Side-Rear PoP out Windows?

I am building a 74 Duster race car. I thought it would be neat to keep the rear side pop out windows, but take the glass out and put poly in. Has any one done this. I have the frames out, but can't figure out how to get the glass out to replace it. I don't want to tear it up by being stupid. Can any of your guys help with some instructions for a old guy?