When the "S" motor was introduced to the public a two peice vibration damper was also introduced. This is reputed to be the best system for vibration control (until the Fisher 'friction' damper was developed) for the Mini motor. The only problem with it was that is was bigger and wider than the other version. And in fact the first of the motors had no damper at all! With the close quarters of the Mini engine compartment the bottom radiator mounting became a problem and thus this special lower brecket was developed. If you are upgrading you might need this simple piece!