DESCRIPTION --Fits Small Block Chevy 265 283 305 327 350 383 400 using a short water pump. --Pulley diameter is 6 9/16". --Pulley is 3/4" tall. --Bolt pattern is 2 3/4". --Center hole is 1 1/8". --Machined from billet aluminum. --Package: Including all items in the pictures. Note: Professional Installation Is Highly Recommended (No Instruction Included).