There is no way to assure that it is a GT. One way to possibly tell is by a hole in the radiator support. The fog light wiring harness runs through a small hole in the radiator support. If the hole looks to be drilled, it is most lilkely not a GT because they were punched from the factory. It should have a rough edge around the hole. It will not give you a definite yes or no but you can make your own assumption from it.