GTS letters could be in red on green, white, and black cars I have seen over the years. I have been looking for the factory paperwork (TSB) on them for years, still haven't found it.
My GTS (PP1) had red letters (in poor shape, I might add) when we bought the car in 1983. It had 70,000+ miles. I painted them black in the 1980s because I liked the look better. I will probably go back to red this next time around. You can see the red in this pic. You can also see that the replacement hood (from 1970) was not drilled very straight for the letters.
