The glass is the same size but the mechanisms can differ from model to model. For example, the Granada stuff fits in some cars and not in others as it's all to do with the protrusion of the winder spline through the roof.

Also, they work on a cable system which is coiled to the plastic of the frame of the mechanism so if that snaps you can't actually repair it as it will always jump out again.

Got a spare set up in the garage if you want some pics of what goes wrong.