Eaton Detroit Truetrac Differential - 28 Spline 1.20in Axle 2.73+ Ratio - Select GM 1964-1989 (8.5in)

Fits select 1964-1989 Buick, Chevrolet, GMC, and Cadillac vehicles (including Camaro, LeSabre, and C1500) equipped with an 8.5-inch rear end and 28-spline axle shafts.

The Eaton Detroit Truetrac (MPN: 912A556) is the industry-leading helical-gear limited-slip differential (LSD). Unlike traditional clutch-style differentials, the Truetrac uses a gear-based design to manage torque distribution without the need for friction modifiers or wearable clutch packs. This results in a maintenance-free unit that provides smooth, quiet operation in both forward and reverse.

Engineered for durability and traction, the Truetrac automatically senses wheel slip and transfers torque to the wheel with the most grip. Its high torque-bias ratio provides maximum acceleration and improved handling on the street, track, or trail. Because it operates as an open differential until wheel slip occurs, it remains completely transparent during normal driving and tight maneuvering.

• Axle Spline Count: 28
• Axle Shaft Diameter: 1.20 in
• Ring Gear Diameter: 8.5 in
• Gear Ratio Compatibility: 2.73 and numerically higher
• Material: High-strength forged steel housing with helical internal gears
• Operation: Maintenance-free; no friction modifiers or special additives required
• Manufacturer Part Number: 912A556