1966 barracuda rear window regulator & door Assem?
You should be able to unbolt the regulator with it's glass attached, and get it to a position where you can unbolt the glass from the track. Once you get the glass out, the regulator can be removed. Good luck on getting it to free up and work again. When they get really rusty, they can get pretty stubborn. Just be careful trying to free it up. If it breaks, it can snap against your fingers! It might be better to remove the spring first. Just be careful doing it.