Shop the 14-Bolt Overhaul Kit →
Both axles have 14 cover bolts, both are full floaters with 8-lug hubs, and both sit under three-quarter and one-ton GM trucks. The GM 14-bolt is the 10.5 inch full-float axle GM built in-house and ran from the early 1970s through the 2000 model year in pickups and longer in vans. The AAM 11.5 is the American Axle unit that replaced it under the 2001-up Silverado and Sierra 2500HD and 3500, and showed up under the Ram 2500 and 3500 starting in 2003. Nothing inside the third member crosses over between them.
Side-by-Side Comparison
| Spec | GM 14-bolt full float | AAM 11.5 |
|---|---|---|
| Ring gear | 10.5 inch | 11.5 inch |
| Common trucks | GM 3/4 and 1-ton pickups, Suburbans and vans, early 1970s to 2000 in pickups | 2001+ GM 2500HD/3500, 2003+ Ram 2500/3500 |
| Axle shafts | 30-spline, full float | 30-spline on GM, full float |
| Carrier break | 4.10 and down / 4.56 and up | Most stock ratios share one carrier; confirm with the gear set |
| Pinion support | Two tapered bearings plus a pilot bearing on the pinion nose | Large pinion; bearing kits change by year |
| Pinion preload | Crush sleeve; eliminator kit available | Varies by year and kit; follow the kit |
| Ground clearance | Low-hanging pumpkin, often belly-shaved on off-road builds | Better than a 14-bolt, still a big center section |
| Parts cost | Cheap, huge used supply | Higher, more year-specific kits |
Do not mix the full-float 14-bolt up with the semi-float 14-bolt under half-ton trucks. That is a smaller axle with C-clip shafts and 6-lug hubs. If the hub has 8 lugs and a raised center with 8 shaft bolts, you have a full floater.
Ring Gear and Pinion: Where the Strength Comes From
On paper the 11.5 wins: a full inch more ring gear means more tooth contact and a bigger pinion head behind it. Behind a modern diesel, that extra gear is why GM and Ram moved to it. The 11.5 lives behind a stock or lightly tuned diesel pulling a 15,000 lb fifth wheel all day.
The 14-bolt's trick is its pinion. It rides on two tapered bearings plus a pilot bearing at the nose, so the pinion is supported on both sides of the gear mesh and does not walk away from the ring gear under shock load. That is why rock crawlers on 40 inch tires run 14-bolts and rarely break gears. For trail abuse with big tires and low gears, a healthy 14-bolt is as close to unbreakable as a junkyard axle gets.
Mind the 14-bolt carrier break. A truck with 3.73 or 4.10 gears going to 4.56 needs the 4.56-and-up carrier. Going to 5.13 or 5.38, use a thick gear set; the Yukon 14-bolt 5.38 thick gear set ($511.58) is the common pick for 37s and up. For a tow rig staying near stock tire size, the Yukon 14-bolt 4.11 gear set ($484.89) stays on the low carrier.
Bearings, Crush Sleeves and Year Splits
Both axles changed bearings over the years, and that is the number one reason a rebuild kit shows up wrong. On the 14-bolt, older and later pinions take different bearings: there are separate kits for 1988-and-older and 1998-up housings. If the housing date is unknown, read the old bearing numbers before ordering.
Most 14-bolts set pinion preload with a crush sleeve. On a truck that tows, we would rather run a solid spacer and shims; the Yukon crush sleeve eliminator for the 14-bolt ($115.89) holds preload better under repeated heat cycles.
The 11.5 is split by year and by make: 2010-and-down GM and Ram, 2011-up, 2014-up Ram 2500, and 2019-up Ram each have their own overhaul kit. Do not assume a GM kit fits a Ram of the same year. Read the axle tag and order by it, and follow the preload method in the kit for that year.
Hub bearings on both are tapered roller bearings adjusted with a nut, and they fail more often than the differential on trucks that tow. Grease on the inside of the rim or brakes means a hub seal.
Swaps: Which One to Keep
- Towing with a modern diesel: keep the 11.5. It came behind that torque, the parts match the truck, and swapping in a 14-bolt is a downgrade in ring gear size.
- Old square-body or 1988-98 truck, mostly towing: keep the 14-bolt. Rebuild it, add the crush sleeve eliminator, done.
- Off-road on 37 to 40 inch tires: a 14-bolt with 5.13 or 5.38 thick gears and a locker is the cheap, proven build. Shave the bottom of the housing for clearance.
- 1-ton swap under an older truck: 14-bolts are cheap and everywhere. Measure width, spring perch spacing and pinion yoke series (1310, 1350 or 1410) before you buy.
Our GM 14-bolt problems and rebuild guide and AAM 11.5 problems and rebuild guide go deeper on each axle's failures.
Traction: Lockers and Limited Slips
On the 14-bolt, the Yukon Grizzly Locker for the 14-bolt, 30-spline ($890.73) is a full-time locker for trail rigs. A pure trail truck can run the 14-bolt mini spool ($335), but expect tire scrub and chirping on pavement. For a tow truck that sees snow, the Yukon Dura Grip for the 14-bolt, 4.10 and down ($1,246.24) drives normally.
On the 11.5, the Eaton Detroit Locker for the 11.5, 30-spline ($1,607.99) is the heavy-duty standard, and the Yukon Grizzly Locker for GM and Chrysler 11.5 ($1,806.23) is the alternative. A locker behind a loaded trailer on wet roads can push the truck; on a daily tow rig, a limited slip is easier to live with. See our open vs limited slip vs locker guide.
What It Costs: 14-Bolt vs 11.5 Rebuild
| Job | DIY | Shop (rough) |
|---|---|---|
| 14-bolt bearing overhaul | About $300-$700 | About $900-$1,400 |
| 11.5 bearing overhaul | About $650-$950 | About $1,300-$2,000 |
| 14-bolt regear with install kit | About $750-$1,000 | About $1,500-$2,200 |
| 11.5 regear with install kit | About $1,000-$1,400 | About $1,900-$2,800 |
| Hub bearings and seals, both sides | About $200-$350 | About $500-$900 |
| Add a locker, either axle | About $900-$1,800 | Add $400-$800 install |
Fill either one with a quality 75W-90 or heavier synthetic as the truck calls for from our fluids section, plus friction modifier if a clutch-type limited slip is inside. Setup details live in the backlash and pinion depth guide.
Parts and Tools for the Job
| Need | What We Carry |
|---|---|
| 14-bolt full overhaul | GM 14-bolt 10.5 master overhaul kit ($281.99) |
| 14-bolt, 1972-1987 bearings | GM 14-bolt 10.5 master bearing kit, 1972-1987 ($261.99) |
| 14-bolt, 1998+ housings | Yukon master overhaul kit, GM 98+ 14T ($674.95) |
| 14-bolt hub bearings | Yukon 14-bolt axle bearing and seal kit ($189.75) |
| 14-bolt shafts | Yukon 1541H 30-spline 14-bolt axle shaft ($377.54) |
| 11.5 overhaul, 2010 and down | USA Standard 11.5 AAM master overhaul kit ($630.77) |
| 11.5 overhaul, 2011 and up | Yukon 11.5 master overhaul kit, 2011+ ($907.17) |
| 11.5 regear, 2003-2010 | Revolution 03-10 GM/Dodge 11.5 master install kit ($305.99) |
| GM 11.5 hub bearings | Yukon GM 11.5 AAM axle bearing and seal kit ($339.15) |
| Ram 11.5 hub bearings | Yukon 03+ Dodge 11.5 wheel bearing and seal kit ($303.87) |
| 11.5 cover | AAM 11.5 cast aluminum rear cover ($335.99) |
For the transmission and transfer case side of a heavy-duty truck, CoreTransmissionParts.com carries rebuild parts.
Rebuild It Once
Every bearing, race and seal for the 14-bolt in one kit, matched to the axle you actually have.
Shop the 14-Bolt Overhaul Kit → Gear Oil and FluidsFAQ
Is the AAM 11.5 stronger than a GM 14-bolt?
In ring gear size, yes. The AAM 11.5 has an 11.5 inch ring gear against the 14-bolt's 10.5 inch, and it was built to live behind modern diesel torque. The 14-bolt makes up ground with a pinion supported by a nose pilot bearing, which is why it holds up so well on big tires off-road.
Do 14-bolt and AAM 11.5 parts interchange?
No. Both use 14 cover bolts and 8-lug full-float hubs, but the ring and pinion, carrier, bearings, covers and lockers are all different. Order by the axle tag, not by counting cover bolts.
What is the 14-bolt carrier break?
The 14-bolt uses one carrier for 4.10 and numerically lower ratios and another for 4.56 and up. Ratios of 5.13 and 5.38 are commonly run as thick gear sets.
Should I swap a 14-bolt into my 2001+ HD truck?
No. The AAM 11.5 that came under it is the bigger axle and matches the brakes, wheels and driveshaft. Rebuild the 11.5. The 14-bolt makes sense for older trucks and budget off-road builds on 37 to 40 inch tires.