Yukon YG GM12T-373 Ring & Pinion 3.73 Ratio 1963-1987 Chevy GMC 8.875 12-Bolt

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Product Specification:

SKU:YUKYG GM12T-373

MPN: YG GM12T-373

UPC: 883584241287

Weight: 13.6 lb

Type: Final Drive Gears

Vehicle Fitment

1963-1987 Chevrolet C10 (2WD/4WD, All Engines)
1963-1987 Chevrolet K10 / K1500 (4WD, All Engines)
1963-1987 Chevrolet Suburban (2WD/4WD, All Engines)
1969-1974 Chevrolet Blazer (2WD/4WD, All Engines)
1969-1987 Chevrolet K5 Blazer (4WD, All Engines)
1967-1981 Chevrolet G10 Van (RWD, All Engines)
1963-1987 GMC C15 / C1500 (2WD, All Engines)
1963-1987 GMC K15 / K1500 (4WD, All Engines)
1963-1987 GMC Suburban (2WD/4WD, All Engines)
1966-1981 GMC G15 / G1500 Van (RWD, All Engines)

Fitment Notes

This is a STANDARD (thin) gear set - fits carriers with a 3.73:1 and higher (numerically) ratio; requires standard thin-style carrier case
Does not fit thick carrier cases designed for 3.42 and lower factory ratios - verify carrier break before ordering
GM 8.875" 12-bolt truck differential has carrier breaks at 2.73 / 2.76-3.42 / 3.73; confirm your existing carrier series before purchasing
1963-1964 applications require a 30-spline yoke - verify yoke spline count prior to installation
Does not fit the GM 8.875" 12-bolt passenger car differential - truck and car versions are not interchangeable

Features

High-performance ring and pinion engineered specifically for the GM 8.875" 12-bolt truck differential - precision fit for factory carrier cases
Gear tooth surface finish optimized to reduce friction and heat buildup under sustained high-torque and towing loads
Manufactured from high-grade steel with advanced heat-treating for long-term durability on and off road
Designed to OEM specifications for proper backlash, contact pattern, and pinion depth - reduces setup time and risk of gear noise
Standard rotation ring gear - direct replacement for factory GM 12-bolt truck applications
3.73 ratio delivers a strong balance of low-end torque for towing and hauling while remaining practical for highway use
Backed by Yukon's Y.E.S. Plan - lifetime, no-questions-asked coverage for as long as you own the vehicle
Validated through Yukon's two in-house quality labs for metallurgical composition and dimensional accuracy

Specifications

Differential Application: GM 8.875" 12-Bolt Truck (Rear)
Gear Ratio: 3.73:1
Gear Style: Standard / Thin (fits 3.73 and up carrier)
Ring Gear Diameter: 8.875"
Ring Gear Teeth: 41
Pinion Gear Teeth: 11
Pinion Spline Count: 30
Pinion Shaft Diameter: 1.438"
Ring Gear Bolts: 12
Cover Bolts: 12
Ring Gear Rotation: Standard
Carrier Series: Fits 3.73 and up carrier case
Position: Rear Differential

Included Components

1x High-Performance Ring Gear
1x High-Performance Pinion Gear

Product Description

The Yukon YG GM12T-373 is a high-performance standard ring and pinion gear set built for the GM 8.875" 12-bolt truck differential in a 3.73:1 ratio. Compatible with classic Chevrolet and GMC trucks, Suburbans, vans, and Blazers from 1963 through 1987, this gear set is the ideal choice for builders re-gearing vehicles that already run a 3.73 or higher factory carrier case. Unlike the thick (373T) variant, this standard gear set is designed to drop directly into existing 3.73-and-up carrier cases without requiring any carrier modification or swap.

Yukon engineers the gear tooth surface finish to minimize friction and thermal buildup, resulting in quieter operation and extended gear life under demanding conditions. Both the ring and pinion are produced from high-grade steel using advanced heat-treating processes, with all dimensions held to OEM specifications for a clean contact pattern and straightforward setup. The 3.73 ratio is one of the most popular choices for classic GM truck builds, offering meaningful torque improvement for towing, hauling, and off-road use without sacrificing driveability at highway speeds.

Before ordering, confirm your carrier case series - the GM 8.875" 12-bolt truck axle has carrier breaks at 2.73, 2.76-3.42, and 3.73, and this standard gear set is intended specifically for the 3.73-and-up carrier. If your existing carrier is set up for 3.42 or lower, see the YG GM12T-373T thick gear variant instead. A ring and pinion installation kit, crush sleeve, and bearings are sold separately and strongly recommended for a complete rebuild. All Yukon gear sets include coverage under the Y.E.S. Plan - lifetime protection for as long as you own the vehicle.