Full Spool 8.5in 30 Spline 10 Bolt GM

The PEM Full Spool 8.5in 30 Spline 10 Bolt GM is a heavy-duty differential spool engineered for full-power axle applications in GM 10-bolt rear housings. This is not a limited-slip unit—it's a true spool that locks both wheels together under all conditions, delivering maximum traction for vehicles requiring aggressive off-road capability, drag racing, or extreme load hauling. The 8.5-inch diameter and 30-spline configuration match factory GM dimensions, ensuring direct bolt-in compatibility without modification to existing housings.

Built from steel with a durable black powder-coat finish, this spool handles full engine torque and shock loads typical of high-performance drivetrains. The 30-spline design distributes stress across more contact points than lower-spline alternatives, reducing wear and improving longevity under sustained heavy load. At 10.75 pounds, the spool is precision-balanced to minimize vibration once installed. The compact 9 x 8.8 x 9.1-inch footprint confirms factory-spec packaging, critical for vehicles where suspension geometry is already optimized around OEM differential dimensions.

This spool is built for users who demand maximum traction and accept the trade-off: both wheels turn at the same speed on all terrain, including pavement. It is the standard choice for serious off-road trucks, high-powered drag vehicles, and any application where lock-up during acceleration or climbing is non-negotiable. The GM 10-bolt platform is one of the most common rear housings in truck and Chevelle builds, making this spool a direct replacement for factory open differentials or worn limited-slip units.