To be an actual GT, it would have had to come with a 4 barrel Carb. V8 The GT/CS is a model that was made specifically as a promotional car. Only certain DSO's got these cars to sell. It's almost like the 2001 Mustang "Bullitt Edition", that was a promotional car, or look at the 40th Anniversary edition of the Mustang. I saw a 40th edition of the convertible and it was sort of rare due to it's production, and the promotional aspect of that paticular model. All 2004 40th anniversary mustangs have the emblems, but there were only a few that were made specifically as promotional, ie...color, console options, color of interior, special emblems...etc...
The GT/CS was a promotional car for 1968 and certain dealers sold these cars. The fact that the GT on the GT/CS might make some confussed, the fact is that an actual GT had a V8 that was 4bbl, also the suspension was beefed up and then there were the wheel options. The regular mustang had a GT option that included a GT package that included the fog lights, GT emblems and gt options.
All California Specials had the GTCS on the side scoops, but what make it a real GT is that the GTCS had to have come with a 4bbl V8.
Like previuosly posted, Alot of the GTCS's came with the V8 289 2bbl, This would not be an actual GT, but the car is still a GTCS.
If you can find P Newitts recognition and owners manual, you will have a book with all the facts about the GTCS, it explains it's origin and the story about how this car came about.
Theres a registry that was started and is updated on this web site. If your not in the registry and do have one of these cars, it help to locate and keep track of these jewels.
IMOA, if you have a GTCS, and it's a C code or any other codes ie... J, S, X, Q, R, or even T code, you still have a GTCS and these are rare cars to me and others. The fact that these are rare and fun and eye catching. Just remember, California Made it Happen!