Heavy-Duty SFI Flexplate1963-1982 Small Block Ford 289-351W164-Tooth28 oz. CounterweightExternally BalancedBolt Pattern (11.50 in.)14.13 in. Diameter x 0.140 in. ThickChromoly SteelSFI 29.1 Rated JEGS 601096 Heavy-Duty Flexplate for use with 1963-1982 Small Block Ford 289-351W 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.