Heavy-Duty SFI Flexplate1971-1979 Mopar 383, 400, 440 with TF727No Ring GearExternally BalancedDual Bolt Pattern (10 in. & 11.125 in.)11.750 in. Diameter x .147 in. Thick6-Bolt Crank PatternChromoly SteelSFI 29.1 Rated JEGS 601088 Heavy-Duty Flexplate for use with Mopar 383, 400 and 440 externally-balanced engines is engineered to handle extreme-duty applications and designed to take the punishment of today's high-horsepower engines. This Flexplate is .035 in. thicker than stock and has a 29.1 SFI approval stamped into the face of the plate.