The big plastic interior 1/4 panels you see when you look in the backseat, thats what we're talking about, right? If they have paint flaking off, they've been painted in the past, the 71-73 panels were made using plastic that was the color of the interior (at least both sets I've experienced have been). But, to take the paint off I wouldn't use any kind of strong chemical stripper, might eat through the plasitic. I would try some very fine steel wool or something first, then when I got mad enough because that didn't work I'd go to something harsher /forums/images/icons/wink.gif. Good luck!
BTW, if you don't already have them out of the car, do it, much easier that way.
-Jason
'72 Mach 1 || '90 Talon TSi AWD
http://nosaj122081.tripod.com/parade3.jpg
"Thats not a leak, my car's marking its territory!"
"If you've done it, it ain't braggin'." -Roy Rogers