PRW 1830204 SFI-Rated External Balance 157 Teeth Chromoly Steel Flexplate for Ford 289-351W 1963-82 SFI 29.1 certified 0.035 inch thicker than stock flexplates Designed and built for racing Manufactured to exceed OEM specifications Features double-welded ring gears designed to withstand the RPM and stress of engine torque related to high stall converters