Every '04 is a 40th Anniversary Mustang, but they made a special 40th Anniversary package for a limited amount of GT's. Three colors-Crimson red, black, and white. Color matched side view mirrors, striping on hood, rocker panel, and rear decklid. 17" Bullitt wheels. Interior upgrade package, with 40th Anniversary floor mats, and some kind of badge on the console. Same engine and everything else. Just a cosmetic package.