Why are you looking for GTS doors in particular? I didn't know there was a difference... My GTS came with power locks/windows, so I believe mine would be the same as a GT...?
Your power windows/locks doors on your GTS are even MORE rare! The car itself (gts) is wired completely different than GT's and powered optioned V6's. When I had my GTS, I had to replace the entire body harness to make my GT doors (pulled from my wrecked GT) work. The GT door harnesses would not mate to the body harness at all, totally different. At the junkyard I saw that all the V6 Mustangs (powered) had the same plugs as my GT doors and body harness had. So the body harnesses on the GTS Mustangs are unique to those and V6 non-powered windows/locks cars. It's even hard to find V6 cars with manual crank windows! Come to think of it, I believe ALL Mustangs have power locks... Hope that made sense.
Damn! I'm surprised about the whole wiring thing now. Come to think of it, out of the 3-4 GTS's I've seen in my area, I'm actually the only one who isn't manual everything.
Unfortunately, whoever originally ordered mine got most of the power locks, windows, and AC.....would much rather have manual and save the weight. Not that it matters with the car not being driven for 5 years right now, but for the future anyway.