Duster rear bumper question

is there actually a 73 bumper or is it just left over 72 stuff that was used?
In the case of the 4-door, the 72 rear bumper is the same as the 73 less a re-inforcing bar and the big rubber blocks. I know that the taillight panel for the 73 Duster was different from the 72. What I am unable to do is tell you that the older bumper will fit properly with an appropriate gap between the bumper and the sheet metal.

Given the cash situation at Chrysler at the time and the low profitability of the a-body, I don't see Chrysler investing any more in the platform than they absolutely had to. It would not surprise me that the older bumper with its mounts would not bolt right up. I just can't say for sure.