Agreed with the fenders being rare... the '71s have the split front reflectors that are inside the body... in '72 and '73 they went with a much simpler single bar reflector that (if I recall correctly) sticks out a little from the sheet metal. If you're not picky they do swap back and forth, but it won't be "correct".
I'm fairly certain the front doors are the same between sedan and wagon, but the back doors are not- the area around the window is rounded on the back part of the door to fit with the sedan's roofline, and squared off to flow into the back quarter window on the wagon.
There's been a "NOS" '71 fender on ebay for quite awhile... going for more than I paid for the car.