Differential Cover 77-90 GM Truck 8.5in 10-Bolt

The Differential Cover 77-90 GM Truck 8.5in 10-Bolt is purpose-built protection for the rear axle assembly on second-generation GM trucks and SUVs. This stamped steel cover seals the differential housing, protecting internal gearing from road debris, mud, and moisture while containing gear oil—critical components that transfer engine torque to the wheels under load. Whether you're running stock gearing or upgrading to higher ratios, this cover is essential maintenance hardware that every truck owner should verify is properly sealed and intact.

Manufactured by Specialty Products Company, this differential cover fits the 8.5-inch 10-bolt rear axle—the workhorse differential found in most full-size Chevy and GMC trucks from 1977 through 1990. The stamped steel construction provides rigid sealing against the housing flange, and the bolt pattern integrates with factory mounting points for straightforward installation. A fresh gasket seal ensures oil retention and prevents leaks that can lead to premature bearing wear and gear damage. The compact dimensions (10.55 x 3.25 x 10.9 inches) and 2.45-pound weight make it easy to handle during axle service or rebuild work.

Truck enthusiasts and mechanics replace differential covers during routine maintenance, after road damage, or when performing gear ratio upgrades and limited-slip conversions. This cover is ideal for anyone restoring a square-body Chevy truck, refreshing an aging drivetrain, or simply replacing a cracked or leaking original. Proper fitment is guaranteed on 77–90 GM trucks equipped with the 8.5-inch 10-bolt rear, making it a reliable choice for both street and off-road applications where axle integrity matters.