1936-69 style oil pump. Includes primary scavenge port machining. Machined for 1965-69 alloy primary. Engines for 1936-64 chassis with tin primary must use a 1954-64 style inner primary cover. S&S Super Stock generator style crankcases are available for stock 3-7/16" or 3-5/8" bore. 1936-54 must use the 1955-64 style inner steel primary cover. Since all S&S generator style crankcases use 1958 and later style main bearings, stock flywheel assemblies 1957 and earlier cannot be used in S&S crankcases. Flywheel assemblies must have 1958 and later pinion shaft with 1.250" diameter bearing, and a 1954 and later style sprocket shaft designed for a Timken main bearing. Generator style cases for 1936-47 knucklehead engines are machined to supply oil to the heads from a boss located near the rear tappet guide or from a stock or S&S gear cover. Crankcases for 1948-69 engines are machined with a provision to separate the oil supply to the top and bottom ends if an S&S oil pump is used. This feature lets you choose the 1972 and earlier stock "side oiling" system or the 1973 and later split oil system. The stock cast iron oil pump can be used. If an S&S billet oil pump is used, the oiling system can be set-up as stock or updated to a split system. 1963-65 Panhead engines, with outside oil supply lines to the cylinder heads, must use the oil supply port located behind the rear tappet guide or the oil fitting toward the rear of the S&S gear cover. S&S generator style crankcases do not have the stock style oil supply boss, so special oil supply lines will need to be fabricated.; ; Features natural finish For 1965-69 Big Twin Models 3-5/8" bore