Revolution Gear & Axle GM 14-Bolt 10.5in Rear Axle 5.38 Ratio Thick Ring & Pinion Set
The Revolution Gear & Axle GM10.5-538T is a 5.38 thick ring and pinion for the GM 14-bolt 10.5 in. full-floating rear axle. It is the deepest ratio Revolution makes for this axle, and the people who need it are running 40 in. or larger tires, a crawler or mud build on a 14-bolt, or a 3/4-ton Chevrolet or GMC that has been lifted and loaded until the factory 3.73 or 4.10 gears leave it bogging at every light. It also replaces a chewed-up gear set in a 14-bolt that has been whining since its last trip off-road.
Revolution lists this set with a 10.5 in. ring gear, a 30 spline pinion, twelve ring gear bolts, standard rotation and 8620 steel. The 14-bolt supports its pinion with two tapered bearings and a pilot bearing at the nose, which is why it handles 5.38 gearing better than most axles. At 5.38 the pinion head is small, so the ring gear is made thicker to put the teeth back where the pinion meets them. That thick gear is built to bolt to the 4.10-and-down carrier. Revolution gives the carrier break as 4.10/4.56, and the thick design means a truck with factory 3.73 or 4.10 gears can keep its stock carrier, Positraction or locker instead of buying a new one. If you are adding traction anyway, the Dura Grip for 14-bolt 4.10-and-down carriers fits the same case. Our carrier break explainer covers why thick gears exist.
Make sure you have the 10.5 in. full-float 14-bolt and not the 9.5 in. semi-float 14-bolt or an AAM 11.5. Look for 14 cover bolts with a hub that sticks out past the wheel, then read the ratio from the axle tag or RPO code. Our 14-bolt problems and rebuild guide and the 14-bolt vs AAM 11.5 guide show how to tell them apart. To decide whether 5.38 is right for your tire size, use the regear after bigger tires guide. Match the front axle too: a 4x4 needs the same ratio front and rear.
Revolution's fitment list for the 4.56-5.38 thick 14-bolt set covers 1999-2004 Chevrolet Silverado 2500 and GMC Sierra 2500, 2001-2015 Silverado 2500 HD and Sierra 2500 HD, 2007-2013 Silverado 3500 HD, 2000-2013 GMC Yukon XL 2500, 2002-2006 Avalanche 2500 and 2001-2006 Silverado 1500 HD. GM also put the AAM 11.5 under many heavy-duty trucks of the same years, and 1500 HD trucks are best checked by cover bolts and hub style before ordering. Older 14-bolt trucks and vans also used the same axle, so check the axle itself rather than the model. Send us your year and VIN if you are not sure, or see the 5.13 thick 14-bolt set if 5.38 is more than your build needs.
Revolution's setup chart for the GM 10.5 lists a 0.017 in. starting pinion depth, 20-35 in-lb pinion bearing preload, 0.006-0.010 in. backlash, 120 ft-lb ring gear bolts and 135 ft-lb bearing caps. Replace the pinion bearings, pilot bearing, carrier bearings and seal with the Revolution 14-bolt master install kit, and consider the crush sleeve eliminator for a pinion that holds preload under big tires. Fill with 75W-90 or 75W-140 gear oil and follow the break-in procedure before towing or wheeling.
| Brand | Revolution Gear & Axle |
| Part number | GM10.5-538T |
| Fits | Revolution Gear & Axle GM 14-Bolt 10.5in Rear Axle 5.38 Ratio Thick Ring & Pinion Set |
| Type | Ring & Pinions |
| 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.
Not if your axle has 3.73 or 4.10 gears now. This is a thick gear set made for the 4.10-and-down carrier. Axles that came with 4.56 or deeper gears use the other carrier, so check your ratio before ordering.
On a 3/4-ton truck with an overdrive automatic, 5.38 is usually chosen for 40 in. and larger tires or for heavy rock crawling. Smaller tires generally call for 4.56 or 4.88. Our regear guide walks through the math for your tire and transmission.
No. It fits only the GM 10.5 in. full-floating 14-bolt. The 9.5 in. semi-float 14-bolt and the AAM 11.5 use different ring and pinion sets.
Yes, on a 4x4 the front and rear ratios must match or the transfer case and tires will bind in four-wheel drive. Order the 5.38 set for your front axle at the same time.
Use a master install kit with new pinion, pilot and carrier bearings, races, seal and shims, plus fresh 75W-90 or 75W-140 gear oil. Recalibrate the speedometer for the new ratio and tire size after the job.
