Yukon Gear Dura Grip Limited Slip Differential for GM 12 Bolt 30 Spl 2.76-3.42 Ratio

If your C10, K10, G-van or early Blazer spins the inside rear tire pulling out of a wet driveway, or the old factory posi has long since worn into an open diff, this is the carrier to look at. The Yukon Gear & Axle Dura Grip, part number YDGGM12T-3-30-1, is a clutch-type limited slip for the GM 12-bolt truck rear axle with 30-spline shafts, built for the taller ratio range from 2.76 through 3.42.

What the Dura Grip does in a 12-bolt truck axle

With an open carrier, torque always takes the easiest path, so a light rear end on a half-ton pickup will spin one tire on gravel, wet grass or ice while the other one does nothing. The Dura Grip sandwiches composite clutch plates between the side gears and the case. Preload springs and the push of the spider gears under throttle clamp those plates, so both axle shafts are tied together and the tire with grip gets driven. When you turn a corner the clutches slip and let the outside wheel run faster, so the truck still drives normally on pavement.

Yukon builds it with a nodular iron case, forged 4320 chromoly spider gears and composite clutches, assembles it in the USA, and the whole unit can be rebuilt with new clutches later instead of replaced.

Signs your truck needs a new limited slip

• One rear tire spins while the other stays planted on loose or slick ground
• With one rear wheel off the ground and the transmission in neutral, it spins freely and the other wheel turns the opposite way: no working clutch pack
• Chatter, shudder or a groan in slow tight turns from worn clutches or the wrong oil
• Clunk on and off the throttle from worn thrust washers or a cross shaft that has walked
• A broken or cracked factory case found during a gear or bearing job

How to confirm before you buy

The truck 12-bolt and the passenger car 12-bolt share an 8.875 in. ring gear size and a twelve-bolt cover, but carriers do not interchange. The truck cover is an irregular shape while the car cover is a smoother oval, and our YK GM12T truck overhaul kit page walks through the other differences. Pull an axle and count splines; this unit is 30-spline only. Then read the axle code or count gear teeth. Ratios from 2.76 to 3.42 drop straight on. If you are running 3.73 or deeper, use the 3.73-and-up 12-bolt truck Dura Grip instead, unless you have thick 3.73-and-up gears; Yukon notes this carrier also accepts those.

Fitment

Yukon lists this part for the GM 12T differential with 30-spline axles and 2.76-3.42 gear ratios. GM used the 12-bolt truck axle in Chevrolet and GMC half-ton C and K pickups, G-series vans and 1969-1981 Blazers, and it stayed in some light trucks into the 1980s. Early trucks had spline and housing variations, so do not assume every 12-bolt truck is 30-spline. Check the cover, spline count and ratio, or send your year and VIN and we will confirm before it ships. It is not for the passenger car 12-bolt or the 9.5 in. and 9.76 in. 12-bolt used in 1999-and-later GM trucks.

Install notes

Moving the ring gear to a new carrier changes backlash and carrier bearing preload, so treat it like a gear setup. Press new carrier bearings on (the GM 12-bolt truck master bearing kit has them), use new ring gear bolts, and check backlash and the contact pattern. Yukon's chart for the 12-bolt truck lists about 0.006-0.011 in. backlash, 55 ft-lb on the ring gear bolts and 60 ft-lb on the caps. Install the C-clips through the cross shaft opening, then the cross shaft and its lock bolt.

Oil matters with composite clutches. Yukon recommends a high-grade non-synthetic GL-5 gear oil plus its limited slip additive, and warns that synthetic oil can make the unit noisy or aggressive. Drive a few figure eights in a parking lot after the fill to seat the clutches. If you ever rebuild it, Yukon sells replacement Dura Grip composite clutches that cover the 12T.

Will this fit my 1972 C10 with a 3.07 rear?

If it is the 12-bolt truck axle with 30-spline shafts, a ratio in the 2.76-3.42 range fits this carrier. Some trucks of that era came with a 10-bolt instead, so check the cover bolts and shape first, or send your VIN.

Does it fit a Chevelle or Camaro 12-bolt?

No. The passenger car 12-bolt uses a different carrier. Use the 12-bolt car Dura Grip for that axle.

I am regearing to 4.11. Which carrier do I need?

Use the 3.73-and-up 12-bolt truck Dura Grip. This unit is for 2.76-3.42, though Yukon notes it also accepts thick 3.73-and-up gears.

What gear oil should I use?

Yukon recommends a non-synthetic GL-5 gear oil with its limited slip additive. Synthetic oil can make the clutches grab and chatter.

Can I reuse my old carrier bearings?

It is not worth it. Install new carrier bearings and races when you change carriers, then reset backlash and check the pattern.