This 6 5/8" diameter crankshaft pulley was originally installed on high performance 1962-68 302 and 327ci V8s. Its two deep grooves are designed to retain the fan belts at high rpm. This pulley fits small-block V8 and V6/90 engines with short water pumps. ID #19355269. Can be used with water pump pulley P/N 3770245 and captured belt P/N 9433722 without an idler pulley or alternator.