For 9" or 9-1/2" Ford standard 28 spline pinion pro gears, with dual angular contact rear bearings. Requires MW yoke or coupler. Drilled for 7/16" studs to accommodate studs used in all MW cases. However, with special reducer bushings (p/n 57606) and studs (p/n 57609), the housing can be used with 9" Ford cases that have 3/8" threads. All pinion supports come pre-assembled. The bearing pre-load is set through the use of a solid hardened pre-load spacer rather than a crush sleeve or stack of thin shims. The spacer is factory machined to the required preload for each assembly. Pinion seals are included. Stock Ford yokes must be shortened for proper pinion nut thread engagement. Installation - Service instructions can be found on Service Bulletin #0097.