Toolman is right. The Blue Streak was part of the Rallye Pack that included fast ratio manual steering like the Formula S package. Also included in the pack that was worthwhile was a front anti-sway bar. Here's my old 273 Hi-Po 66 GT A/C, DB restored to 97 point form. (Nicked 2 points for radials and one for the radiator cap.) It's a non-Rallye Pack car.
Blue streaks were standard on all Dart 273 4-barrel GTs with 14 inch wheels regardless. My car has disc brakes, optional 3.55 suregrip and the H-D Suspension package (rallye pack), and there is no fast ratio box.