Yukon Gear Dura Grip Positraction For GM 12 Bolt Car w/ 30 Spline Axles / 3.73+
This carrier is for the square-body or earlier GM half-ton that has been regeared deep for big tires or towing and still pulls with only one rear wheel. Yukon Gear & Axle part number YDGGM12T-4-30-1 is a Dura Grip clutch-type positraction for the GM 12-bolt truck axle (Yukon code 12T) with 30-spline shafts and 3.73 or numerically higher gears: 3.73, 4.10, 4.56 and beyond. One note before anything else: the listing title says Car, but Yukon's own description and part number say 12T, and the published fitment is all trucks, vans, Blazers and Suburbans. If you own a Chevelle, Camaro or Nova 12-bolt, you need the passenger car carrier instead, linked below.
Deep gears multiply torque, and on an open 12-bolt that extra torque simply spins the lighter tire faster. The Dura Grip stacks composite clutch discs and steel plates between each side gear and the case. Spring preload keeps a baseline grip on the clutches, and once you get on the throttle the spider gears push the side gears outward, clamping the packs harder. The result is that both axle shafts are tied together in proportion to the load, so the tire with traction keeps pulling. When you turn, the outside wheel overrides the clutches and the truck corners like it has an open carrier. Yukon specifies a high-strength nodular iron case, forged 4320 chromoly spider gears, and a fully rebuildable design assembled in the USA.
Why a separate 3.73-and-up unit? As ring gears go deeper, the gear itself gets thicker, so the mounting flange on the case has to sit in a different spot. Yukon splits the 12-bolt truck Dura Grip into a 2.76-3.42 version and this 3.73-up version for that reason. Our carrier break explainer shows how to tell which side of the break your gears are on.
The 12-bolt truck and 12-bolt car share an 8.875 in. ring gear but do not share carriers. Our 10-bolt vs 12-bolt guide covers the cover shape and other tells. Next, pull an axle and count the splines; this unit takes 30. Then find your ratio by dividing ring gear teeth by pinion teeth. If it works out to 3.42 or taller, order the 12-bolt truck Dura Grip for 2.76-3.42. A car axle with 3.08-3.90 gears takes the 12-bolt car Dura Grip.
GM ran 10-bolt and 14-bolt axles in some of these same trucks, so the model year alone does not prove a 12-bolt. If you are not sure, send us your year, VIN and a photo of the cover and we will check it. Other carriers and gear sets are in our hard parts collection.
| Brand | Yukon Gear & Axle |
| Part number | YDGGM12T-4-30-1 |
| Fits | Yukon Gear Dura Grip Positraction For GM 12 Bolt Car w/ 30 Spline Axles / 3.73+ |
| Type | Differentials |
| 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. The part number YDGGM12T-4-30-1 is the 12-bolt truck carrier, and every published application is a GM truck, van, Blazer or Suburban. A passenger car 12-bolt needs the 12P Dura Grip.
No. This version is built for 3.73 and numerically higher ratios. For 2.76 through 3.42 on a 12-bolt truck, use the 2.76-3.42 Dura Grip so the ring gear seats correctly.
Yes. It covers 3.73 and numerically higher ratios on a 30-spline 12-bolt truck axle, which is the range deep tire-and-gear swaps use.
Yukon recommends a high-grade non-synthetic GL-5 gear oil with its limited slip additive. Synthetic oil is not recommended because it can cause aggressive or noisy clutch engagement.
Yes. The Dura Grip is fully rebuildable, so when the composite clutches wear you can replace the clutch pack instead of the whole carrier.
At minimum new carrier bearings and races, since the old ones stay on the old case. Most builders also replace the pinion bearings, pinion seal and crush sleeve with a master kit, and use new ring gear bolts.
