Very hard to find, especially the original Mopar ones. @Cudahunter may be the best source for info on them. I think he may know something about them, but maybe not?
Terry W.
If you refer to the rubber door-ding protector trim running along the body line, I think those were dealer installed, not an OEM factory part. So there may be several options that will work and look vintage.
Here's a few pieces I have that follow the body lines of the Challenger. They had female plastic pieces slid into the molding channel on the back which were then attached to the male metal pins on the fenders, door and rear quarter panels. The pins looked like the pins used to hold the clips for the exterior windshield trim moldings. When I removed these, I had to weld up alot of holes after removing the pins.
Terry W.