Nicholas,

If you have just joined one month ago with little lurking beforehand, let me warn you that there are many knowledgeable people on this site, some of whom are married to their "facts". Sometimes individual's "facts" differ from those of others, and bickering ensues. As a matter of fact, just my observation of this might itself cause bickering. This behavior is not limited to online boards - I spent a fair amount of time two weekends ago listening to someone patiently explaining just how 'wrong" my seat belts were, because he'd never seen anything like them.

Let me divide my comments into personal experience / empirical observation, and hearsay that was represented to me as "fact" by knowledgeable persons.

Personal experience / empirical observations:

I have owned a 1970 Challenger R/T convertible (SPD 9/15/69) since 1979. At the time I purchased it, there was nothing to lead me to believe anyone had tampered with the seat belts. The fender tag was present, but the buildsheet was missing (or perhaps discarded on my watch in Tijuana at an upholstery shop). On the fender tag is the code C15 - Deluxe Restraint System. On the dash is a red light that turns on with the courtesy circuit, and stays lit for a variable amount of time (ranging from as little as 10 to as much as 30 seconds) after the courtesy circuit goes off. The length of delay seems to increase, the longer the courtesy lights were lit. My seat belts are push-button style, with a white band around the perimeter. Although they [the female portion] appear slightly larger than the 71-ish push button style, the MALE portion appears to be the same (and firmly/solidly mates with either style). Attached is a photo with the Deluxe next to a 71-ish sample. You will notice the difference in size, button shape, top embossing, and white perimeter banding.

I have personally seen many other E body convertibles (R/T and otherwise) without this C15 group. It is, in my experience on the planet, a rare item.

Hearsay:

The bezel and mounting stuff is the same as the reverse light, with the exception of the lens.

In rare situations, it can be found on 4-speed cars, in which case the factory punches another hole, and the two lights are side-by-side.

The seat belts can also be found on selected C-bodies (although I have never seen this, and might be willing to buy the whole dang car just to get the rear belts that my car now lacks because of what some foolish kid did back in the 80's [please don't compare this date with my date of acquisition]).

I hope this helps. (You got any belts like mine?)