There were two different trunk floors put into a 1971 Challenger during the 1971 production year. The floor changes at the end of May 1971 and really is a 1972 trunk floor. The change is for shock assess holes in the floor. Early on top, late facing rear of trunk. There are still original late trunk floors for a Challengers for sale at most Chrysler show, Carlisle or the Nationals. AMD did sell both early and late Challenger trunk floors. You would have to look it up to see if they still do.