I am having an after market rear valence with cutouts installed on my 71 challenger. There is a pic below. My body guy is wondering if there are additional brakets that are missing to hold the panel in place. There seems to be holes for bolt that are not there. Much thanks for any help.

1970 used a different mounting setup than 71-74. Your 71 should just have one bracket in the middle of the valence.

Also, your going to have to remove that triangular lisense plate bracket. I can see it in your picture. That bracket was used in 73-74 only. In those years, the rear bumper was held away from the body farther than 70-72. The lisense plate needed to be held out farther because of it.

Thanks for the tips.