Part Number MCC600 Steel Triple Plated Copper / Nickel / Chrome For Small Block Chevy Engines 1957 - 1969 With SHORT WATER PUMP Small Block Chevy Water Pump Pulley Is Made From .050 Thick Steel SB Chevy Water Pump Pulley Has A Diameter Of 7 1/8 Inches SBC Water Pump Pulley Is A Single Groove Pulley Pulley Is A Short Water Pump Pulley And Has A 1 3/4 Inch Bolt Pattern Water Pump Pulley Has A Back Space Of 2 3/4 ".