Yukon Gear Hardcore Nodular Iron Cover for Rear GM 8.6in w/8mm Cover Bolts
Owners of 1999 and newer Silverado 1500, Sierra 1500, Tahoe, Yukon, Avalanche, Escalade and Express or Savana 1500 vans with the GM 8.5 or 8.6 inch 10-bolt rear eventually deal with the same weak spot: a thin stamped cover with metric bolts that seeps at the bottom, rusts along the flange, and folds in the first time it lands on a rock. The Yukon YHCC-GM8.5-M Hardcore cover is the nodular iron replacement for that metric housing. It ships with 8 mm cover bolts, a magnetic drain plug and a fill plug, and wears a black powder coat with a stainless accent plate.
The later GM 10-bolt, usually called the 8.6, is a C-clip rear axle with the ring gear, carrier and cross pin sitting just inside the rear cover. On a lifted half-ton or a Tahoe running bigger tires, that cover is the lowest, most exposed part of the axle. Nodular iron is far tougher than the factory stamping, so it shields the ring gear and any locker or posi you have upgraded to. Tying the open back of the housing together with a rigid casting also reduces flex in the carrier area under towing and launch loads, and the contoured interior returns oil across the gears for cooler running. A built-in drain plug lets you change fluid without disturbing the cover seal.
Make sure the cover is the leak before buying. Oil at the yoke is the pinion seal, oil on the inside of a tire is an axle seal, and a wet cover flange is the cover itself. Our differential cover leak guide walks through it. If the axle is also whining, check the GM 8.5 and 8.6 10-bolt problems guide before closing it back up, and see our fluid change interval guide for how often to service it.
This version fits the GM 8.5 and 8.6 inch 10-bolt rear axle with 8 mm metric cover bolt threads, listed for 1999-and-newer trucks and SUVs including the Silverado 1500 and Sierra 1500 (1999-2019), Tahoe, Yukon and Escalade (1999-2019), Suburban and Yukon XL 1500, Avalanche, and Express and Savana 1500 vans (2000-2014). Many of those vehicles were also built with the larger 9.5 or 9.76 inch 12-bolt rear, which this cover will not fit, so count the cover bolts: this one is for ten. Yukon flags 1998 and 1999 as transition years with either 5/16 inch or 8 mm threads, so pull a bolt and check it. Earlier inch-thread housings need the 5/16 inch bolt YHCC-GM8.5-S cover. When in doubt, send us your year and VIN.
Drain the axle, pull the old cover and remove every bit of old sealer from the housing face. Clean the 8 mm threads, apply a gasket or a thin RTV bead inboard of the bolt holes, then hand-start all ten bolts and tighten them evenly in a crisscross pattern. Refill with 75W-90 gear oil through the fill plug with the truck level, plus friction modifier if the axle has a clutch-type limited slip such as the Yukon Dura Grip for 30-spline axles. If the bearings are tired, the 1999-2008 GM 8.6 master overhaul kit renews them while the axle is open, and a 3.73 face-hobbed ring and pinion is the common regear for bigger tires.
| Brand | Yukon Gear & Axle |
| Part number | YHCC-GM8.5-M |
| Fits | Yukon Gear Hardcore Nodular Iron Cover for Rear GM 8.6in w/8mm Cover Bolts |
| Type | Diff Covers |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. Some 1999-up GM trucks came with the 9.5 or 9.76 inch 12-bolt rear. This cover only fits the 10-bolt 8.5 and 8.6 inch housing with 8 mm cover bolts.
The castings are made for the same 10-bolt 8.5/8.6 pattern, but this kit includes 8 mm metric bolts for the later housing. Order YHCC-GM8.5-S if your housing is threaded for 5/16 inch bolts.
Yes. It includes 8 mm cover bolts, a magnetic drain plug and a fill plug, along with the stainless accent plate.
A Hardcore cover is thicker than a stamped cover, so check clearance to the exhaust, spare tire and any rear sway bar before installing, especially on vans and lowered trucks.
75W-90 gear oil is the usual fill for the GM 8.6. Add limited slip friction modifier if your axle has a clutch-type posi and the oil does not already include it.
