You know, I bought 2 rear pans, one for cuda and one for challenger. The cuda fit very well and has factory quarters , the challenger has factory quarters too and I took the original valance off to put a dual exhaust repop on the back. I had trouble with the same drivers side as you did and it done the same thing. I am thinking it may have been an off brand bad run we got ahold of and they passed it on to the customer.