I can't help you with the part number portion of your question, but from my experience, all Challenger rear trim panels will interchange, fitment-wise, from year to year. There are some variations, such as some had ashtrays, or a cut-out slot for the shoulder belts on a 74. I know of no difference in window crank positions.
The only difference that I am aware of fitment-wise, is there were 2 variations on the screw holes. It was either different position of a couple of holes, or a different number of holes.
Hope this helps you...
