These are 4 lug 10" vented rotors. This is a great swap if you can find the whole rear end! It is a 8.8" rear end, and the stock gear ratio is 3.55 for the manuals, 3.73 for the autos on the Turbo Coupes, and 3.08 on the 93 Cobra. Keep in mind the axle is .75" wider than the stock Mustangs, you...