Motive Gear 3.73 ring and pinion set in 8620 steel for the GM 7.5 and 7.625 inch 10-bolt rear axle, 41/11 teeth with a 27-spline pinion.
The Motive Gear GM7.5-373A is a 3.73 ring and pinion for the small GM 10-bolt, the 7.5 inch and 7.625 inch rear axle found under S-10 and Sonoma pickups, S-10 Blazer and Jimmy, Camaro and Firebird, and the G-body Monte Carlo, Cutlass, Regal and El Camino. Buyers are usually doing one of two things: swapping a tall 2.73, 3.08 or 3.23 highway gear for something that pulls hard off the line, or replacing a factory 3.73 that has started to whine. The listing cross-references this set to GM 26036813.
The pinion takes power from the driveshaft and drives the ring gear bolted to the carrier. With 41 teeth on the ring and 11 on the pinion, the driveshaft turns 3.73 times for every turn of the axles, compared with roughly 2.7 to 3.2 turns in many factory economy gears. That shift multiplies torque at the tire and puts the engine in a stronger part of its rpm range, which is why 3.73 is the go-to gear for a V8 swap or a move to taller tires. Per the manufacturer data, the ring gear is 7.5 inches with 10 ring gear bolts, the pinion has 27 splines and a 1.438 inch shaft, and both gears are standard rotation 8620 steel.
First make sure the axle is a 7.5 or 7.625 and not the larger 8.5: the small 10-bolt has an oval cover about 8 5/16 by 10 9/16 inches. Then check the existing ratio on the axle tag or the RPO code in the glove box, or count driveshaft turns against one tire turn. The most important check is the carrier. This set must be used with a carrier built for 3.23 and numerically higher ratios. Axles that came with 2.73, 3.08 or 3.42-and-lower ratio families may have a different carrier series, and the ring gear will not sit at the right height on it. A carrier change pairs well with a Dura Grip posi for 28-spline 7.625 axles, 3.23 and up. Our axle ratio and code guide shows where to read the numbers, and carrier break explained covers why it matters.
The listing covers the GM 7.5 and 7.625 inch 10-bolt rear axle used from 1973 through 2013 in Chevrolet, GMC, Buick, Cadillac, Oldsmobile, Isuzu and Hummer cars and light trucks. The 7.5 and later 7.625 share the 27-spline pinion and gear dimensions, but bearings, axle spline counts and carriers changed over those years, so match the cover shape, the 27-spline pinion and your carrier to this set, or send us your year and VIN. If your axle has a 3.08 carrier and you want to stay mild, our 3.55 thick-gear 7.5 set is the alternative. Common failures on this rear are covered in GM 7.5 and 7.625 10-bolt problems and rebuild cost, and more axle parts are in our hard parts collection.
This is the gear set only, with no bearings, shims, crush sleeve, seal or ring gear bolts. For 1982-1999 axles the ZK GM7.5-B master overhaul kit supplies all of them. Pull the C-clips and axles before the carrier comes out, mark the bearing caps so they go back on the same sides, and drive out the old pinion races. Set pinion depth with the shim behind the inner pinion bearing, crush a new sleeve to the correct rotating preload, then set backlash with the carrier shims and read the contact pattern with marking compound. Fill with 75W-90 gear oil and add friction modifier if the axle has a clutch-type posi. Drive gently for the first few hundred miles without towing or hard launches, then change the oil.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Not always. The GM7.5-373A must be used with a carrier built for 3.23 and numerically higher ratios. Lower ratio axles can use a different carrier series, so confirm yours before ordering or plan on a carrier or posi swap.
Yes. The set is listed for the GM 7.5 and 7.625 inch 10-bolt with the 27-spline pinion.
41 teeth on the ring gear and 11 on the pinion, which gives the 3.73 ratio.
A master overhaul or install kit with pinion and carrier bearings, races, shims, crush sleeve, pinion seal and ring gear bolts, plus a dial indicator, an inch-pound torque wrench and marking compound.
75W-90 gear oil, plus limited slip friction modifier if the axle has a clutch-type posi. Change it after break-in.
Yes, any ratio change alters the speedometer reading. Older trucks change the speedometer gear and newer ones are reprogrammed for the new ratio and tire size.
