Part #(MCC924) Installation tips: Make sure that you have a keyway pump. It will have a notch in the shaft and the pulley will be held on to the power steering pump by a nut (NOTE: pulleys with washer marks or scratches cannot be returned) Material Chrome steel , triple plated Copper / Nickel / Chrome Hole Size This pulley is for a 5 /8 shaft which is the size all gm keyway style pumps are Keyway This Chrome Power Steering Pump Pulley is for keyway style power steering pumps Nut   Chrome pulley Does Not come with mounting nut your stock nut will fit the same Thickness The chrome pulley is stamped from approximately .060 thick steel. Diameter  The diameter of this chrome 2 groove Power Steering Pulley is  5 3/4" Two Groove This pulley is a 2 Groove pulley for GM keyway power steering pumps" Back Space This pulley has a 1 1/8" back spacing Belt Chrome V belt pulley uses a standard 3/8 belt size Application  Chrome power steering pulley is for Olds Pontiac Small and Big Block Chevy Restrictions Cannot be run on press on style power steering pumps Comments: We have matching chrome water pump pulleys chrome alternator pulleys and chrome crankshaft pulleys if you want to complete your engine Check Out these related items All our chrome pulleys can be reached by clicking here CHEVY CHROME PULLEYS