Loaded open carrier with spider gears and carrier bearings for the GM 8.5 and 8.6 inch 10-bolt rear axle, 30-spline, 2.73 to 5.13 ratios.
A clunk when you take off, a knock that only shows up while turning, or a cross shaft that walked out and chewed up the case on a Silverado, Sierra, Tahoe, Suburban, Yukon, Avalanche or Escalade usually ends with a new carrier. This is a complete open differential carrier for the GM 8.5 and 8.6 inch 10-bolt rear axle with 30-spline axle shafts. It arrives loaded, with side gears, spider gears and the cross shaft installed, and it ships with a pair of tapered carrier bearings. It replaces GM carrier numbers 40048044 and 19244836, and it covers the 2.73 through 5.13 ratio range.
The ring gear bolts to the flange of this case, so everything the pinion drives turns the carrier. Inside, the cross shaft holds two spider gears that mesh with the two side gears, and the axle shafts slide into the side gears on their 30 splines. On a C-clip 10-bolt the case is also what holds the axles in: the C-clips sit in the side gear bores and are trapped there by the cross shaft and its lock bolt. That is why a broken lock bolt is so destructive on these axles. The shaft drifts out, the C-clip falls loose, and the axle and shaft can hammer the case and the ring gear before anyone notices.
Pull the cover, rotate the carrier and look at the cross shaft lock bolt and the spider gear teeth. Rock one tire back and forth with the other held: a lot of free play before the pinion moves points to worn spiders and thrust surfaces. Rumble that follows road speed is more often a carrier bearing, explained in our carrier bearing noise guide, and clunk sources are covered in rear end clunk when accelerating. On a truck with a 4L60E, also rule out the transmission with our 4L60E noise diagnosis guide before tearing into the axle.
Listed fitment is the GM 8.5 and 8.6 inch 10-bolt rear with 30-spline axles under 1988-2018 Chevrolet and GMC 1500 trucks and SUVs, Escalade and Avalanche, plus 1999-2004 S10 and 2002-2008 Trailblazer and Envoy. Several of those vehicles were also built with the smaller 7.5 or 7.6 inch axle and 28-spline shafts, which this case does not fit, so confirm a 10-bolt 8.5 or 8.6 with 30-spline axles before ordering. It is a standard open carrier, not a posi or locker; if you want traction, look at the Dura Grip positraction or the Grizzly locker instead. The GM 8.5 10-bolt problems guide shows how to tell the axles apart. If you are not sure, send us your year and VIN.
If the pinion bearings are worn too, do them while it is apart: the GM 8.5 master overhaul kit suits the older 8.5, and the 1999-2008 GM 8.6 overhaul kit suits the later axle.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, it is listed for the 8.5 and 8.6 inch 10-bolt rear with 30-spline axles. It does not fit the 7.5 or 7.6 inch axle or 28-spline shafts.
The case covers 2.73 through 5.13 ratios, so most factory and common aftermarket gear sets bolt on without a different carrier.
No. It is a standard open carrier with spider and side gears. For traction, use a positraction or locker made for the 30-spline 8.5 and 8.6.
Use new ring gear bolts with thread locker. These are stretch-sensitive fasteners, and a backed-out ring gear bolt can destroy the case and gears.
Yes. A new case will not sit exactly where the old one did. Shim for backlash and carrier preload, then check the gear pattern before closing the cover.
75W-90 gear oil, filled to the bottom of the fill hole. An open carrier does not need friction modifier.
