I have no personal knowledge, but I have seen it in several places that, basically, corresponding year GM pickup boxes will fit, I think a bolt on.

These have a faster ratio, or variable ratio.

I have looked at some, but never had them both off the trucks at the same time, but they sure LOOK interchangeable.

And I think the Dodge box is a Saginaw, too.

Thing is, I am looking at my 85, and don't know about the 72 box.

There was something weird about the 4wd boxes, I can remember installing P/S on an early one (72 3 or naybe74)and after finishing up, starting it, and the wheels went in opposite direction of what the steering wheel was turned.

I can't remember exactly what the screw up was, 2wd box or before/after date of steering changeover, or what, but for some reason I DO remember it was a red short bed Adventurer w150.