PRW 1845400 SFI-Rated External 168 Teeth Balance Chromoly Steel Flexplate for Chevy 454 1970-90, Early 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