Ford 10.25 Rear Differential Master Bearing Kit, Koyo

This is the Motive Gear R10.25RMK rear master bearing kit for the Ford 10.25-inch rear axle, the Sterling housing Ford put under three-quarter and one-ton trucks from the mid-eighties through the late nineties. It is a master kit, not a bearing-only kit, so it carries the parts you actually consume during a setup: Koyo tapered carrier bearings, front and rear pinion bearings, pilot bearing where the application uses one, a crush sleeve or preload shim pack, pinion nut, pinion seal, carrier and pinion shims, cover gasket, and gear marking compound with a brush.

Fitment covers 1985-1998 Ford F-250, 1985-1997 F-350, the 1997 F-250 HD and F-450 Super Duty, 1988-1997 F-Super Duty, 1988-1997 F-53 motorhome and F-59 commercial stripped chassis, and 2000-2003 F-150 models built with the 10.25 axle. Confirm the ring gear measures 10.25 inches before ordering, because Ford also used the 10.5-inch Sterling in the same body styles and the bearings are not interchangeable. It cross-references Ratech 341K, Dorman 697-112, Richmond Gear 83-1059-1, EXCEL XL-1059-1, Revolution Gear K35-2046, USA Standard ZK F10.25, and Motive Gear R10.25RMKT.

On the bench the sequence is the usual one: pull the carrier, press the old races out of the housing, drive the new Koyo races in square, set pinion depth with the shim pack and check the wear pattern with the marking compound before you commit. The crush sleeve gets collapsed to spec on the pinion nut for preload, then carrier bearing preload is set with the side shims and backlash checked on a dial indicator. Having the correct shims and a fresh crush sleeve in the box is the difference between one setup and three trips to the parts counter.

This is the kit to reach for when a 10.25 starts howling on decel, when the pinion seal keeps weeping after the nut has been re-torqued, or any time you pull a cover and find spalled carrier bearings or blue-tinted rollers from a low-fluid run. Motive Gear backs it for 1 year or 50,000 miles.