Air Cooled engines had two types of cams. 1961 to 1971 had a Flat cam that had three rivots and a Dished cam 1972 to 1979 that had four riviots. If you are going to upgrade or relace your oil pump, you first need to know what cam you have and the order the pump to match the cam. If you are going to order an aftermarket performance cam, you will need to purchase an oil pump for a flat cam. All performance cams have a bolt on cam gear that is a Flat gear. In the photo below, the early style cam is on the left and the dished cam is on the right.