In the Dr Diff 13" kit that's $850, the calipers are Mustang Cobra...not the base mustang. I can't remember if the rotors are c4 vette or for the same mustang cobra though. Just tell 'em you have an 03 Mustang Cobra.
The 13" Dr. Diff kit uses C4 Corvette rotors that are re-drilled with the 5x4.5" bolt pattern. And it uses Mustang Cobra calipers. They would be a great match the either of Dr. Diff's rear disk kits, although I'd be leaning to the 11.7's myself.
