Eaton 913A481 Detroit Truetrac LSD for GM 8.5-8.6" 30-Spline Rear (2.73+ Ratio)

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Product Specification:

SKU:EAT913A481

MPN: 913A481

Weight: 26.4 lb

Type: Differentials

Vehicle Fitment

1988-1999 General Motors Half-Ton / Three-Quarter-Ton Trucks & Vans with GM 8.5" 10-bolt C-clip rear (30-spline axles, 2.73 & up gears)
1999-2013 GM vehicles with GM 8.6" rear 30-spline axles and 2.73 & up gear ratio
2006-2009 Hummer H1 / H2 / H3 Rear (GM 8.6" 30-spline, 2.73+ gears)

Fitment Notes

Requires correct bearing size: small bearing bore (race O.D. ≈ 2.89") for pre-1999 axles (bearing LM102949 / race LM102911); large bearing bore (3.06") for 1999-2013 axles (LM603049 / race LM603012).
Only works with ring & pinion gear ratios **2.73 and numerically higher** (steeper).
Will not fit GM 8.5/8.6" axles with thick ring gears that exceed clearance or with incorrect carrier breaks. Verify gear thickness.
Cover bolt count is 10; will replace Limited Slip or open 8.5/8.6" carriers with matching housing.

Features

Helical gear design delivers smooth, automatic torque biasing without clutches or friction plates.
Full-time limited slip performance - works in both forward and reverse.
Maintenance-free operation; no wearable friction modifiers or periodic adjustment required.
Compatible with various GM rear axle applications (10-bolt C-clip 8.5", 8.6") over a wide model year span.
Robust construction with 30-spline axle shafts (1.32" diameter) to handle higher torque loads.
Supports a wide range of ring & pinion ratios (2.73 & up) for flexibility in performance or stock gearing.
Weighs approximately 26.1 lb - relatively light for its capacity.
Quiet and smooth gear action thanks to Eaton's Truetrac engineering.

Specifications

Ring gear size: **8.5" / 8.6"**
Axle shaft spline count: **30** splines
Axle shaft diameter: **1.32 in**
Permitted ring & pinion gear ratios: **2.73 and higher** (numerically larger)
Cover bolt count: **10 bolts**
Differential type: Helical-gear Limited Slip Differential (LSD)
Product weight: **~ 26.1 lb**
Finish: Carrier steel, standard internal finishes per Eaton spec; no special coatings listed

Included Components

1x Eaton Detroit Truetrac differential carrier assembly (part # 913A481)

Product Description

The **Eaton 913A481 Detroit Truetrac** is a high-performance, gear-driven limited-slip differential engineered for GM 8.5"/8.6" rear axle housings. If you're upgrading from an open differential or tired clutch-type LSD, this Truetrac delivers superior traction, especially in worst-case scenarios like wet roads, snow, or noted torque bias situations. Its helical gear setup means torque shifts automatically to the wheel with more grip, all while remaining smooth and quiet during normal driving.

It fits 30-spline axle shafts of 1.32" diameter and supports ring & pinion ratios starting at 2.73 and steeper. Important installation details include ensuring your axle housing uses the correct bearing configuration (pre-1999 / post-1999 bearing bore size), verifying gear thickness/carrier break compatibility, and using only Eaton-approved GL-5 80W-90 mineral gear oil. This unit is ideal for street performance, towing, off-road light duty, and muscle car applications. Fitment is confirmed through 2024. 2025 unconfirmed.