Fits mainshaft and countershaft on big Twin, Countershaft on Sportster 1991-later. A high horsepower/torque engine mandates that the drive train be upgraded to eliminate possible failure. Be safe by installing this four point style access door bearing. Unlike the OE style deep groove bearing that is only designed for slightly more than the stock horsepower at best, this four point bearing has a radial capacity that is double that of a deep groove bearing and an axial capacity that is many times greater. This four point bearing features a two-piece inner race and includes 10 ball bearings as opposed to the 8 ball bearings that the OE style deep groove bearings have.