Those holes are for the large rubber 5mph absorbers on the 74 model year Javelins. They bolted to the bumper and had a sort of strap that extended down and bolted thru the rollpan to the nuts. Most likely a previous owner removed them and left the holes. The front valance and the rear rollpan had them. I removed them and tig welded plugs in the valance and rollpan to cover the holes and had the body guy smooth the plugs up for paint. A rollpan from a 71-73 should bolt right up. 68-70 may work but I'm not positive. I still have the huge things in the shed if you are interested. I think they were the only ugly thing on the 74 Javelins.