OK. There is some confusion about the tail lights being used on these fenders.
What light depends on what series it is on. The 1x6/7, 1x8/9, QL and the 82 Series all shared a similar fender pan. They are the same shape, but there are some differences in the 3 main series here.
The 1x6/7 used the Grote light that was shown in Post 2 from CC Specalties. This light is like what I have seen on semi’s that have the 2 bulbs. There are a “rounded” rectangle on the base, and where the lights are are actually raised. The face of the lens is not flat. (I have actually used the same light on my 1450… but)
The 1/x8/9 and Quietline use the rectangular ones that are shown in Post 10, these are not the same as the ones that were used on the 1x6/7, These are very “square” it has all shape lines and the sides are fairly flat.
The 82 Series use the ones that are almost flat, and the bulb twists in from the back (above the tire). The above 2, your remove the lens to replace the bulb). I believe this is the “Vega” lights that are being referenced.
This is not to be confused with the single round Grote light used on the Original and maybe the 70/100, and the single Post 2 style that goes next to the IH on the back of the 1x/4/5 that I have seen….