Eaton’s Detroit Truetrac truly is a piece of engineering artwork. With a helical gearset that automatically provides maximum traction to both wheels, it’s the latest evolution in a long line of limited-slip differentials that stretches back more than five decades.

“The Truetrac operates as a standard (open) differential under normal driving conditions, allowing for unobtrusive operation. When a wheel encounters a loss of traction or the terrain changes, the helical-shaped gears mesh with increasing force, transferring torque to the high traction wheel until wheel spin is slowed or completely stopped,” Eaton explains. Unlike a standard locker with its all-too-familiar “clank” around corners, the Truetrac’s engagement is seamless.

Inside, there are no clutches or cones to wear. In fact, the Truetrac doesn’t even require any special friction modifiers; regular ol’ GL5-rated 80w-90 gear oil will do just fine. It all stems from the magical helical gears that are about as close to maintenance-free as you can get in a differential.

The latest addition to the Truetrac lineup is one for 2011-current Ram 1500 trucks with a 9.25” ring gear and 31-spline axles (P/N 917A730). Commonly known as the “ZF 9.25,” this rear made its way into a great many Rams with both the V6 and V8 under-hood.

A factory limited-slip differential has always been optional, but leaves a lot to be desired in harsh conditions or when larger tires are installed. The Truetrac’s revolutionary design offers both an upgrade from original and peace of mind for the long-haul.