The Eaton Detroit Truetrac is a helical gear-driven limited-slip differential that maximizes available traction while sharpening handling and drivability. It engages smoothly and automatically, needs no maintenance, and suits street, tow, and trail use without the on/off behavior of a full locker. It is built for the Ford Super 8.8in C-clip rear axle in a 34-spline fitment.
Specifications
- Type: Helical gear limited-slip differential
- Axle: Ford Super 8.8in C-clip (rear)
- Ring gear diameter: 8.8in
- Axle shaft diameter: 1.36in
- Spline count: 34
- Gear ratio: 3.31 and up
- Part number: 917A739
Vehicle Applications
- 2015-2025 Ford F-150 (rear axle)
FAQ
Which vehicle uses the 917A739 Truetrac?
It fits the Ford Super 8.8in C-clip rear axle in the 2015-2025 Ford F-150.
What gear ratios does it work with?
It is designed for 3.31 and numerically higher ratios on the Ford Super 8.8in axle.
How many splines is the 917A739?
It is a 34-spline unit for the Ford Super 8.8in rear axle.
Is the Truetrac maintenance-free?
Yes. The helical gear design engages automatically and needs no clutches or routine service.

