Rear bumper installation pics

Here is a few pictures of my 72 duster (should all be the same as your 71 bumper mounting wise) from before,during and after paint.

I welded on new quarter panels and a tail panel. my originals were really rough and the PO had attempted repairs in the past aswell so....I am not sure if any of my pics are exactly what you need but I hope it helps.

Also I left the very end bumper brackets off the car since I didnt have them anyway....And I just put bolts in the bumper itself to fill the hole. the bumper is still firmly planted to the car just fine. If yours will be a daily driver and put in situations where you or someone else may at some point possibly hit your bumper.....of course it would be a good idea to use those brackets. I personally took the risk without them because the damage the car had when I originally got the car was alot worse than it should have been due to those brackets being connected (instead of just a curl in the bumper where it got bumped....those brackets also damaged the quarter panel).....just personal preference though