Eaton 913A481 Detroit Truetrac Limited Slip Differential GM 8.5/8.6 30 Spline

The Eaton Detroit Truetrac 913A481 is a helical-gear limited slip differential designed for GM 8.5 and 8.6 inch 10-bolt rear axles with 30-spline, 1.32 inch diameter axle shafts and gear ratios of 2.73 and numerically higher. As the first helical gear differential introduced into the automotive aftermarket under the Eaton brand, it remains the leading helical gear-type limited slip differential in the industry.

Key Features:

• Helical-gear design maximizes wheel traction and enhances driving characteristics with maintenance-free, smooth, automatic operation in forward and reverse
• Proven helical gear design eliminates wearable parts, resulting in maintenance-free traction recognized for toughness and quiet operation
• Automatically transfers torque to the high-traction wheel when terrain changes or traction loss occurs through gear separation forces
• Patented parallel-axis planetary helix gears provide quiet, automatic torque splitting
• Sealed unit requires no limited slip additive or adjustments—no clutches to wear out like factory posi units
• Versatile design makes it ideal for almost any vehicle type

How It Works: The differential operates as a standard or open differential under normal driving conditions, allowing wheels to rotate at different speeds as needed, then automatically resumes normal operation when exiting low-traction situations.

Important Installation Notes: All Eaton differentials for GM 8.5 and 8.6 inch axles require special bearings. For axles with small bearing bores found on vehicles prior to 1999, bearing LM102949 and race LM102911 are required; for vehicles from 1999-2013 with large bearing bores, bearing LM603049 and race LM603012 are required. Eaton recommends petroleum/mineral based GL-5 80W90 gear oil—do not use synthetic oil or friction modifiers.

Applications: Suitable for extreme off-road, circle track, drag racing, street and muscle, work truck/towing, light trail/sand sports, rock crawling, and restoration applications.