Pontiac Big Block Crankshaft Pulley, V-Belt, 1 Groove (350 - 400, 428 & 455). Made in the USA from 6061-T6 Billet Aluminum. Underdrive Ratio Increases Horsepower by 10 - 20 HP. Requires 1968 or newer dampener. Requires 1969 or newer water pump (4.5" from flange to engine block).
