Yukon ZG GM8.5-373 GM 8.5in/8.6in 10-Bolt Ring Pinion 3.73 for 1970-1998 GM

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Product Specification:

SKU:YUKZG GM8.5-373

MPN: ZG GM8.5-373

UPC: 883584362142

Weight: 18.4 lb

Type: Final Drive Gears

Vehicle Fitment

1970-1998 GM 8.5"/8.6" 10-bolt rear differential, used broadly across:
Chevrolet Camaro (1970-1981), Nova, Chevelle/Malibu, Impala, Caprice, Monte Carlo, El Camino
Chevrolet/GMC C10/C1500 and K10/K1500 pickups
Chevrolet/GMC Suburban, Blazer/K5 Blazer, and S10 Blazer/Pickup
Chevrolet/GMC G-series and Express/Savana vans
Pontiac Firebird/Trans Am and select Buick/Oldsmobile full-size RWD models

Fitment Notes

Covers both the GM 8.5" (1970-1998) and the physically similar 8.6" design; confirm your ring gear diameter and pinion spline count match before ordering, since axle specs can vary by exact production year
30-spline pinion only; some GM 8.5" applications used a 28-spline pinion instead - confirm your spline count before ordering
Standard rotation only
A rare bolt-in-axle "BOP-style" variant of the 8.5" was used in some 1971-1972 Buick, Oldsmobile, and Pontiac models - verify your differential type if your vehicle falls in that range
This is a ring & pinion gear set only - it does not include bearings, races, shims, or seals; pair it with a separate install or master overhaul kit for a complete gear swap

Features

High-performance ring & pinion gear set for the GM 8.5"/8.6" differential
3.73 gear ratio
30-spline pinion
10 ring gear bolts
8.500" ring gear diameter
Manufactured by USA Standard Gear to exceed OEM specification
Designed for quiet, precise operation and straightforward setup
Backed by a 1-year warranty against manufacturer defects

Specifications

Differential: GM 8.5"/8.6" 10-bolt
Ratio: 3.73
Pinion spline count: 30
Ring gear bolts: 10
Ring gear diameter: 8.500"
Warranty: 1 year against manufacturer defects

Included Components

1x Ring gear
1x Pinion gear

Product Description

The Yukon ZG GM8.5-373 is a high-performance ring & pinion gear set for the GM 8.5"/8.6" 10-bolt rear differential, one of the most widely used rear axles in GM history - found under everything from Camaros and Chevelles to full-size trucks, Suburbans, and Blazers across nearly three decades of production. At a 3.73 ratio, this set is a common choice for restoring proper drivability after a tire size change, or for improving off-the-line torque on a performance build.

Built with a 30-spline pinion, 10 ring gear bolts, and an 8.500" ring gear diameter to match factory GM 8.5"/8.6" specifications, this set is engineered for quiet operation and straightforward setup. Because this axle was used across so many different GM divisions and body styles over such a long run - with some early years using a 28-spline pinion instead of 30, and a rare bolt-in-axle variant appearing briefly in the early 1970s - confirming your exact axle spec before ordering is the key step.

This is a gear set only, not a full install kit - it doesn't include the carrier bearings, pinion bearings, shims, or seals needed to complete a gear swap. Pair it with an appropriate master overhaul or bearing install kit for your specific application. Installation requires differential disassembly and proper backlash and pinion depth setup, so it's best handled by an experienced DIY installer or a differential shop.