Yukon YK GM12T Master Overhaul Kit for GM 8.875" 12-Bolt Truck Differential

Regular price: $159.95
Regular price: ~~$296.00~~
Sale price: $159.95

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Product Specification:

SKU:YUKYK GM12T

MPN: YK GM12T

UPC: 883584140689

Weight: 6.6 lb

Inventory: 4

Type: Differential Overhaul Kits

Vehicle Fitment

1964-1974 Chevrolet C10 Pickup (2WD)
1975-1987 Chevrolet C10 1/2 Ton (2WD)
1965-1967 Chevrolet C10 Panel (2WD)
1965-1966 Chevrolet Suburban (2WD)
1967-1987 Chevrolet C10 Suburban (2WD)
1969-1974 Chevrolet C20 Pickup (2WD)
1975-1981 Chevrolet C20 (2WD)
1973-1981 Chevrolet C20 Suburban (2WD)
1964-1974 Chevrolet G10 Van (RWD)
1975-1981 Chevrolet G10 (RWD)
1967-1974 Chevrolet G20 Van (RWD)
1975-1981 Chevrolet G20 (RWD)
1964-1974 Chevrolet K10 Pickup (4WD)
1975-1987 Chevrolet K10 / K1500 1/2 Ton (4WD)
1967-1987 Chevrolet K10 Suburban (4WD)
1969-1974 Chevrolet K20 Pickup (4WD)
1975-1981 Chevrolet K20 (4WD)
1973-1981 Chevrolet K20 Suburban (4WD)
1969-1974 Chevrolet Blazer (4WD)
1975-1987 Chevrolet K5 Blazer (4WD)
1965-1967 Chevrolet P10 Series (RWD)
1967-1974 Chevrolet P10 Van (RWD)
1975-1980 Chevrolet P10 (RWD)
1966-1967 Chevrolet P20 Series (RWD)
1968-1974 Chevrolet P20 Van (RWD)
1975-1981 Chevrolet P20 (RWD)
1967-1974 GMC C15/C1500 Pickup (2WD)
1975-1978 GMC C15 (2WD)
1975-1978 GMC C15 Suburban (2WD)
1979-1987 GMC C1500 (2WD)
1979-1981 GMC C1500 Suburban (2WD)
1967-1974 GMC C15/C1500 Suburban (2WD)
1975-1978 GMC C25 (2WD)
1975-1978 GMC C25 Suburban (2WD)
1975-1978 GMC K15 (4WD)
1975-1978 GMC K15 Suburban (4WD)
1967-1974 GMC K15/K1500 Pickup (4WD)
1967-1974 GMC K15/K1500 Suburban (4WD)
1979-1987 GMC K1500 (4WD)
1967-1974 GMC G15/G1500 Van (RWD)
1975-1987 GMC G15/G1500 (RWD)
1966-1981 GMC G25/G2500 3/4 Ton (RWD)
1963-1987 GMC C15/C1500 Suburban (2WD)
1963-1987 GMC K15/K1500 Suburban (4WD)

Fitment Notes

Fits the GM 8.875" 12-bolt truck rear differential - 1963-1987 production span
Not interchangeable with the GM 12-bolt passenger car differential - the truck and car versions use different carriers, pinion bearings, and axle splines and are not compatible
1963-1964 applications used 12-spline axle shafts; later trucks transitioned to 30-spline axles - confirm spline count when sourcing axle components alongside this kit
Ring gear bolts ARE included in this kit
Carrier breaks at 2.73 / 2.76-3.42 / 3.73 - confirm your gear ratio falls within your carrier's break range before installation
The GM 8.875" 12-bolt truck uses a smaller inner pinion bearing (1.438") compared to the passenger car 12-bolt (1.675") - do not cross-reference with car 12-bolt kits

Features

Complete all-in-one master overhaul kit - every required rebuild component for the GM 8.875" 12-bolt truck differential in a single part number
Timken bearings and races throughout - meets or exceeds OEM specification for carrier and pinion bearing positions
Ring gear bolts included - no separate sourcing required for hardware
Comprehensive shim kit for precise pinion depth and carrier preload adjustment
Gear marking compound and brush included for ring-and-pinion contact pattern verification before final assembly
Thread locker, crush sleeve, pinion nut, and differential cover gasket all included
Ideal for gear swaps, locker installs, positraction upgrades, and full differential rebuilds
Backed by Yukon Gear's 1-year warranty against manufacturing defects

Specifications

Differential Application: GM 8.875" 12-Bolt Truck Rear
Fitment Range: 1963-1987
Ring Gear Diameter: 8.875 inches
Ring Gear Bolts: (12) 3/8" x 24 RH Thread (included)
Cover Bolt Count: 12
Pinion Diameter: 1.438 inches
Pinion Spline Count: 30
Axle Spline Count: 30 (aftermarket) / 12 (early 1963-1964 OEM)
Carrier Breaks: 2.73 / 2.76-3.42 / 3.73
Ring Gear Rotation: Standard
Bearing Brand: Timken
Position: Rear Differential
Package Dimensions: 13 x 12 x 3 inches
Shipping Weight: 6 lbs
Warranty: 1 Year against manufacturing defects

Included Components

2x Carrier Bearings and Races (Timken)
2x Pinion Bearings and Races (Timken)
1x Pinion Seal
1x Complete Shim Kit (pinion depth and carrier preload)
1x Ring Gear Bolt Set
1x Pinion Nut
1x Crush Sleeve
1x Thread Locker
1x Gear Marking Compound with Brush
1x Differential Cover Gasket

Product Description

The Yukon YK GM12T is a complete master overhaul kit for the GM 8.875" 12-bolt truck rear differential - one of the most iconic and popular axles in classic Chevrolet and GMC truck history, used across 1/2-ton and 3/4-ton C/K pickups, Suburbans, Blazers, and full-size vans from 1963 through 1987. Widely regarded as a strong and upgrade-friendly platform, the GM 12-bolt truck differential is a favorite for performance builds, gear changes, and locker or positraction installations. This kit consolidates every required rebuild component into a single, application-specific part number using Timken bearings and high-quality small parts.

Unlike the GM 8.875" 12-bolt passenger car differential, the truck version uses a smaller 1.438" inner pinion bearing, narrower carrier, and different axle spline count - the two are not interchangeable. This kit is specifically calibrated for the truck application. Ring gear bolts are included, along with a comprehensive shim set for pinion depth and carrier preload, gear marking compound and brush for contact pattern verification, thread locker, crush sleeve, pinion nut, and differential cover gasket. Early 1963-1964 trucks shipped from the factory with 12-spline axles, while later trucks used 30-spline axles - confirm your axle spline count when pairing this kit with replacement axle shafts or a carrier upgrade.

Builders should note the carrier breaks at 2.73 / 2.76-3.42 / 3.73 - if changing gear ratios across a carrier break, a new carrier will be required in addition to this kit. The YK GM12T is the go-to overhaul kit for anyone restoring, regearing, or building a classic GM truck or Blazer and is backed by Yukon Gear's 1-year warranty against manufacturing defects.