Yukon Gear Hardcore Diff Cover for 14 Bolt GM Rear w/ 8mm Cover Bolts
Later Chevrolet and GMC 2500 and 3500 trucks, vans and Suburbans with the 10.5 inch 14-bolt rear came with a housing tapped for 8 mm cover bolts, and a thin stamped cover that dents easily and starts to weep once its flange is bent. YHCC-GM14T-M is the Yukon Hardcore cover for exactly that late-style housing. It is cast from nodular iron, finished in black powder coat with a stainless accent plate, and bolts on with stainless 8 mm hardware. For a work truck that drags a gooseneck across a pasture, or a lifted three-quarter ton that sees ruts and rocks, it replaces the weakest panel on the axle with one that can take a hit.
The 10.5 inch 14-bolt is a full-floating axle: the hubs ride on their own bearings on the axle tubes and carry the weight, while the 30-spline shafts only transmit torque. That leaves the center section and its cover as the most exposed part of the assembly, hanging just a few inches above the ground in the middle of the truck. All 14 cover bolts clamp around the open back of the carrier housing. A nodular iron cover is far stiffer than a stamping, so besides stopping a rock or a stump from pushing into the ring gear, it ties that opening together and reduces housing flex under heavy towing loads. The internal contours direct gear oil back toward the ring and pinion, which Yukon designs for faster cooling.
Make sure the oil is coming from the cover and not from elsewhere on the axle. On a full-floater, oil on the inside of a rear tire means a hub seal, handled with the Yukon 14-bolt bearing and seal kit, and oil at the front of the housing is the pinion seal. The gasket versus RTV cover leak guide explains how to read the leak path. If the axle is already loud, our 14-bolt problems and rebuild cost guide helps decide whether the gears and bearings need work while the cover is off.
This version fits the GM 10.5 inch 14-bolt full-floating rear axle in the late configuration, where the housing is threaded for 8 mm cover bolts. Older housings use 3/8 inch bolts and need the early YHCC-GM14T-S cover instead. Yukon does not attach a model-year cutoff to the change, so measure rather than guess: an 8 mm cover bolt is clearly thinner than a 3/8 inch bolt, and a 3/8-16 nut will not thread onto it. Ram and later GM heavy-duty trucks with the AAM 11.5 axle take the 11.5 inch Hardcore cover, not this one. Send us your year and VIN if you are not sure which axle you have.
Park level, drain the oil and remove the stock cover. Clean every trace of old sealer from the housing face with a scraper and brake cleaner, and run a tap through the 8 mm holes so the new bolts do not bind before they clamp. Use a cover gasket or a thin, even bead of RTV inside the bolt circle, start every bolt by hand, then tighten them in a crisscross pattern so the cover pulls down flat. Refill to the bottom of the fill hole with 75W-90 or 75W-140 gear oil, adding friction modifier if the carrier is a clutch-type posi such as one rebuilt with the carbon clutch kit for the GM 14T. If the gears need attention at the same time, the Yukon master overhaul kit for 1998-up 14T axles renews the bearings and seals in one pass.
| Brand | Yukon Gear & Axle |
| Part number | YHCC-GM14T-M |
| Fits | Yukon Gear Hardcore Diff Cover for 14 Bolt GM Rear 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.
Yukon describes the 8 mm housing as the late-style GM 10.5 inch 14-bolt and the 3/8 inch housing as the early style, without a published year cutoff. Measure one of your cover bolts to be certain before ordering.
It is not necessary. Yukon makes the Hardcore cover in both bolt sizes, so order the one that matches the threads already in your housing.
No. The AAM 11.5 used in later GM and Ram heavy-duty trucks has a different cover pattern and takes the Yukon YHCC-AAM11-5 Hardcore cover.
Yes. The Hardcore cover ships with stainless steel cover bolts and a stainless accent plate.
75W-90 or 75W-140 gear oil is typical for the 14-bolt. Add friction modifier if your carrier is a clutch-type positraction, and fill to the bottom of the fill hole with the truck level.
