M-6375-F46 (6-bolt) = Billet Steel w/a ring gear of 164-tooth, for 4.6L SOHC Mustang. Has increased RPM capability over stock cast iron or M-6475-D46 nodular iron flywheel. Fits 10.5" & 11" clutch. Meets SFI 1.1. NOTE: 4.6L engines may have 6 or 8 bolts to attach to the crankshaft. Check the engine code before ordering. Romeo-built engines have 6 bolts and Windsor-built engines have 8 bolts. All Cobra engines have 8 bolts. The 8th character in the VIN is (X) for Windsor engine plant or (W) for Romeo engine plant.