Not exactly, at least in '71 the base models had amber lenses with clear bulbs, while the high trim models had clear lenses with amber bulbs. I don't know about the '72s.
Actually not, there was a change over during the 71 model year from clear lenses to amber lenses. All early build cars should have clear lenses and all late build cars should have amber.
IIRC the GTX is the only exception to this "rule" having clear lenses both early and late builds...correct?
Most of my restoration experience is with the GTX and all the '71 GTXs that I have had have come with the clear lenses. I certainly have seen and parted plenty of 71 RRs, most with amber but a few with clear. My notes do not indicate build dates, but they do indicate that the base model RRs make up the bulk of my notes and they were consistently with the amber lenses. I only have a few 71 RRs noted with the clear lenses and they were all highly optioned RRs. In particular, the Decor package RRs that I have notes on, all have the clear lenses. But since I only have a few, it is possible that they were coincidentally early builds.
