Here is the situaiton, I am in the process of installing a new (rebuilt) engine into my '83 533i. The problem is that the bolt holding the distributor rotor to the old engine (a hex bolt) is stripped. Also, the engine I removed, compared to the new engine that will go in, is slightly different where the rotor bolts on. There is no base to bolt the rotor to, though there is another hex bolt. Is there a "slip on" version of the distributor rotor, or a slightly different setup that was implemented later down the evolution of the engine? Thanks.