When i bought my 70 challenger 5 yrs. ago, i did alot of research, i was lucky enough to find the original owner in north carolina, he mailed me pics of the car when he bought it new, and the rear panel was painted semi gloss black.My car is a bumble bee stripe car (black) and the body is hemi orange. when i bought the car, it was painted white, when i was in the prosess of restoring it , i scraped down some paint below the white and found black, but below that, it was orange. So i would assume they did this, probly with a orisol can??? But this car was a dealer lot car, not specially orderd . and the original owner said he did not have that done, (i was curious about that too) I remember many years ago, my neighbor, had a 70 chall. gold, with a bumble bee stripe, and it was also blacked out too, i was about 13 yrs old at the time, and would never forget that car..