The Overbearing is our answer to a nearly century old problem; worn out main drive gear bushings and leaky mainshafts. The Overbearing incorporates a high strength, hardened drive gear nut with a precision ground bearing. Mating the nut and bearing together keeps your mainshaft and main drive gear concentric, eliminating bushing wear, and drastically reducing, if not altogether preventing, mainshaft leaks. Now you can run your pan or knuckle trans with even more horsepower and less time between rebuilds! The Overbearing is intended for all big twin 4 speed transmissions pre-1965.**NOTE** The Overbearing is designed to work in the minimal space allowed in OEM situations. In the event aftermarket clutch baskets or aftermarket transmission sprockets are used, a minimal amount of material may need to be removed from the backside of the clutch basket to allow proper room for the Overbearing. In stock applications, the Overbearing will slightly overlap the taper on the mainshaft, but will maintain approximately .030? clearance between itself and the clutch basket.