A bodies have a hole in the inner fender/apron. The factory used a stamped piece of material spot welded, and tacked it on the tire side.
Scroll down here for a pic. http://www.bigblockdart.com/techpages/4sptech.shtml
I used a piece of 2x2x3/16 flat bar with a 1/2 radius on the corners. Most people never realize it's not factory.