I dont like the "filler" piece on these cars rear bumper. What would have to be done to put a '72 bumper on? Would it just bolt up in place and eliminate the filler piece?

You need to either modify the bumper braces to recess the bumper, or use 70-2 bumper braces and bumper to acheive the look your after,...they are avaliable aftermarket if desired, or used...

You need 70-72 bumper brackets and bumper. The 73-74 bumper bolts to the reinforcing bracket so the spacing on the holes are different. 70-71 bumpers typically do not have slots for a jack where as the 72 does, although I think the slots did show up in late production 71s.

Forgot to mention you will also need 70-72 bumper guards and plastict filler behind them to valance.

Thanks guys.

If you are going to move the rear bumper in, I'd move the front in as well. There are a few square holes in the front bumper brackets just ahead of the stock mounting holes. You can drill out those square holes to 5/8" They become your new mounting holes.