There's a guy selling one on Mofarts.com right now:
1970-1974 Dodge Challenger Rear Valance-Factory Original
Factory original, looks like July 1970 date code, rear valance WITHOUT exhaust cutouts. No rust, straight-never wrecked, but not perfect. Light scratches/dings. Good factory sheet metal. 70-74 Dodge Challenger
100.00 + shipping, pm B1MAXX on Mofarts.com, paypal accepted.
Thanks