This is a brand new machined aluminum single groove alternator pulley for SBC V-belt applications. Fits 55-68 & 69-85 SBC 283-400 This will work on both LONG AND SHORT water pumps due to the alternator bracket making up the distance. Provides a clean, custom look 2.8" diameter.Details:Fits 1955-1968 & 1969-1985 SBC 283-400Works with both Long and Short Water Pumps2.8" DiameterSingle GrooveMachined Aluminum