GM 8.5 Rear Differential Master Overhaul Kit, Timken Bearings

Complete master overhaul kit for the GM 8.5 inch rear differential, the corporate 10-bolt that GM hung under everything from half-ton pickups and Blazers to rear-drive cars and S-10s. This is the Yukon YK GM8.5 kit: every wear part that should be replaced when the housing is open, in one box, so you are not standing at the parts counter with the carrier out and the axle on jack stands.

What is in it: carrier bearings and races, pinion bearings and races, a pinion seal, a complete pinion and carrier shim kit, ring gear bolts, a pinion nut, a crush sleeve, thread locking compound, gear marking compound with a brush, and the cover gasket. The bearings and races are Timken, which matters on a 10-bolt because the pinion bearing preload is set with a crush sleeve and a mismatched bearing set will read a false preload on the inch-pound wrench. The shim kit is what lets you actually chase backlash and a clean pattern instead of reusing whatever shim stack was in there when the gears failed.

On the bench: pull the cover, measure and record existing backlash and pinion depth, then tear it down. Press the old races out of the housing and the pinion bearing off the stem, set new pinion depth with the shims, install a fresh crush sleeve, and torque the pinion nut in small steps while checking rotating torque so you do not overcrush and have to start over with another sleeve. Set carrier bearing preload with the side shims, then paint the ring gear with the marking compound and roll it both directions until the pattern is centered on the drive and coast flanks. Ring gear bolts get the thread locker and go in in a cross pattern.

Fitment note: this kit is for the GM 8.5 inch rear. The 1999 and later GM 8.6 inch rear axle uses a different bearing and shim setup and takes its own kit, so identify the axle by cover shape and ring gear diameter before ordering, not by year alone. This kit contains bearings, seals and hardware only; ring and pinion gears, a carrier, and axle bearings are separate.