Did you have the tailgate down?
If yes, It might just tbe safety switch that prevents the glass from being raised when the gate is open.
Try slamming shut the rear door/tailgate real good, then try raising the glass again.
I think the pattern of the seat upholstery is not so different between '72 and '73. But you are totally right, if not for the other details you mentioned, the door panel trim absolutely gives it away as a 1972.