SKU: DET19587-010
MPN: 19587-010
The Eaton Posi 61-80 GM Truck 12 Bolt 30-Spline differential from Detroit Locker-Tractech is a limited-slip unit engineered for full-size General Motors trucks spanning 1961 to 1980. This differential bolts into the factory 12-bolt rear axle housing and delivers controlled torque distribution across both rear wheels, making it the preferred upgrade for operators and enthusiasts running vintage and classic truck platforms that demand reliable traction without the mechanical complexity of full locking differentials.
The unit accommodates gear ratios from 2.76 to 3.42, allowing builders to tune final-drive characteristics for their specific application—lower ratios favor highway cruising and fuel economy, while higher ratios improve low-end torque for towing, hauling, or off-road work. The 30-spline design provides adequate load-carrying capacity for most stock and mildly modified powertrains without requiring custom driveshaft modifications. Steel construction with natural finish delivers durability in field conditions; the limited-slip design reduces wheel slip during acceleration and cornering without the engagement harshness of a fully locking locker, making it suitable for street-driven vehicles and daily-driver trucks.
This differential is ideal for owners of 1961–1980 GM full-size trucks seeking improved traction for patrol duty, patrol truck restoration, off-road recovery work, or multi-purpose field operations where consistent power delivery to both wheels enhances safety and control. The Eaton Posi platform is known for smooth engagement and minimal maintenance compared to locking alternatives, making it practical for vehicles operated in varied terrain and driving conditions.
Fitment is specific to the 8.875-inch 12-bolt GM rear axle assembly used across the full-size truck lineup during this era. Installation requires removal of the existing differential carrier and proper setup by a qualified technician; gear backlash and bearing preload must be verified during installation to ensure longevity. Weighs 21.58 lbs and ships ready for installation.
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