Yukon Gear Hardcore Diff Cover for 14 Bolt GM Rear w/ 3/8in. Cover Bolts
The 14-bolt hangs lower than anything else under a Chevy or GMC three-quarter or one-ton truck, and on a built rig it is the first thing a rock finds. If the stamped cover on your early 10.5 inch 14-bolt is caved in, seeping gear oil from a bent flange, or you just bolted a junkyard 14-bolt under a Jeep or a Blazer and want it armored, this is the part. The Yukon Hardcore YHCC-GM14T-S is a thick nodular iron cover with a black powder coat, a stainless accent plate and stainless cover bolts, made for the early-style 14-bolt housing that uses 3/8 inch cover bolts. It ships at roughly 21 pounds, which is the clearest sign of how much metal it puts in front of the ring gear.
The GM 10.5 inch 14-bolt is a full-floating axle with a 10.5 inch ring gear, 30-spline shafts and a straddle-mounted pinion. Its name comes from the 14 bolts that hold the rear cover on, not the ring gear, which uses 12. That cover closes the entire back of the center section, so when it is crushed it can touch the ring gear, and when the flange bends the oil walks out until the carrier and pinion bearings run dry. A cast nodular iron cover takes a hit that would fold a stamping, and because it is far stiffer it also braces the open back of the housing so the carrier bearing caps deflect less under heavy torque. Yukon contours the inside to move oil back across the gears faster, which helps a working truck run cooler.
First prove the leak is the cover. Oil running from the front of the housing is a pinion seal, and oil inside the wheel is a hub seal on this full-floating axle, which the 14-bolt axle bearing and seal kit covers. Our differential cover leak guide shows when a reseal alone will do. If the axle already howls, drain the oil and look for chips; worn gears and bearings belong in a full rebuild, explained in our 14-bolt problems and rebuild cost guide.
This cover is for the GM 10.5 inch 14-bolt full-floating rear axle in the early configuration with 3/8 inch cover bolts. Yukon makes a separate late-style version for housings tapped for 8 mm bolts, the YHCC-GM14T-M 8 mm cover, and the two are not interchangeable. To check yours, pull one cover bolt and measure the thread: a 3/8 inch bolt is about 9.5 mm across, noticeably thicker than an 8 mm bolt. It also does not fit the 9.5 inch semi-float 14-bolt or the AAM 11.5, which takes the AAM 11.5 Hardcore cover. If you are unsure what is under your truck, send us the year and VIN.
Drain the axle, pull the old cover and scrape both sealing faces down to clean metal, since old RTV or gasket left on the housing is the usual source of a new leak. Chase the 14 bolt holes with a tap so the new stainless bolts seat fully. Seal it with a cover gasket or a thin bead of gear-oil-resistant RTV, then snug the bolts in a crisscross pattern before final torque. Refill with 75W-90 or 75W-140 gear oil, with friction modifier added if the carrier is a clutch-type posi. If the cover is coming off for a gear swap anyway, the Yukon master overhaul kit for 1988 and older 14T axles and the Grizzly locker for the 14-bolt go in through the same opening.
| Brand | Yukon Gear & Axle |
| Part number | YHCC-GM14T-S |
| Fits | Yukon Gear Hardcore Diff Cover for 14 Bolt GM Rear w/ 3/8in. 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.
Remove one cover bolt and measure the threaded shank or try a 3/8-16 nut on it. A 3/8 inch bolt is about 9.5 mm in diameter. Yukon calls the 3/8 inch housing the early style and the 8 mm housing the late style; order this cover only for the 3/8 inch version.
No. It is made for the 10.5 inch full-floating 14-bolt. The 9.5 inch C-clip axle and the AAM 11.5 used on later GM and Ram heavy-duty trucks each need their own cover.
Yes. Yukon lists contrasting stainless steel cover bolts and a stainless accent plate with the Hardcore cover.
Yukon contours the inside of the cover to circulate oil back over the gears faster for cooling. Fill to the bottom of the fill hole with the truck level rather than going by a fixed number of quarts.
Either works on clean, flat faces. Most leaks after a cover swap come from old sealer left on the housing, so clean both surfaces to bare metal first.