71-73's are easy.
Continuation of SD's post
1) remove interior door panels
3) roll up window
2) Remove Watersheild (if still there)
4) remove the two plastic window stops (be very careful they are brittle and are not reproduced)
5) remove the top window guide (dead center of the top inner edge of door)
6) Unbole the three nuts holding the window glass to the regulator.
7) you may want to mark or scribe around the nuts so you know pretty much how the alignment was.
8) Carefully lift the windows up.
The rear quarter windows are really tricky. The best luck I have is to unbolt the windows from the regulator and let the window go to the bottom of the floorpans. Then remove carefully the regulator. Then wiggle out the windows. Reverse the procedure for installation.
I have not been able to R&R the rear quarter windows w/o first removing the regulator.
All in all it's a lot easier to remove the windows than the door glass for 65-66 mustangs.