S&S sprocket shaft assembly for stock Harley-Davidson flywheels or S&S E style flywheels for 1939 - 53 big twin engines. Comes complete with matching nuts and keys. Harley-Davidson part number 24007-39. Note: All reference to H-D part numbers is for identification purposes only. We in no way are implying that any of S&S Cycle's products are original equipment parts or that they are equivalent to the corresponding H-D part number shown. S&S Part #: 33-2021