Eaton Detroit Truetrac Differential 35 Spline 1.50in Axle Shaft Dia 4.10 & Up Ratio Rear Dana 80
A dually Ram 3500 or Ford F-350, F-450 or F-550 that spins one side of the rear on a wet ramp with a trailer behind it, or a one-ton whose worn clutch posi now chatters and slips, is the truck for the Eaton Detroit Truetrac 915A450. It is a helical gear limited slip for the Dana 80 rear axle with 35-spline shafts, built for ring and pinion ratios of 4.10 and numerically higher. The listing title is cut off; this one is the Dana 80, not a Dana 60.
The Dana 80 is a full-floating rear that carries the heaviest loads in these trucks. A Truetrac replaces the carrier with a gear case: pairs of helical pinions in pockets that, as one wheel starts to spin, generate friction against the case and push torque to the other side. There are no clutches to flatten after a hundred thousand towing miles, nothing to adjust, and it drives like an open rear on dry pavement. Eaton lists the case for 35-spline shafts at 1.52 inch diameter (the listing rounds to 1.50) and says it will also accept OE 3.73 thin gear sets.
Confirm the axle is a Dana 80: a 10-bolt cover on a full-float rear, the axle tag, and often an 80 cast into the housing. The Dana 80 guide's warning applies here too: later Ford pickups mostly moved to the Sterling 10.5 and most GM one-tons use the 14-bolt, so do not assume. Then check the ratio on the tag. Gears of 4.10 and up take this case; 3.73 and lower normally take the 3.73-and-down version, though Eaton notes this one also fits OE 3.73 thin gears. Our Dana 80 problems and rebuild guide covers the noises and wear to check first, and the Truetrac buyers guide shows how ratio breaks work.
Eaton's product selector lists 915A450 for 1994-2002 Chrysler, Dodge and Ram three-quarter and one-ton trucks, vans, wagons, cab and chassis and motor homes with the rear Dana 80, and for 1998-2016 Ford one-ton trucks, vans, wagons and cab and chassis with the rear Dana 80, all at 4.10 and up. Axle choices changed by model, engine and wheelbase within those years, so match the axle tag and spline count, or send us your year and VIN. More heavy axle parts are in the hard parts section.
If you want clutch-type traction instead, compare the Yukon Dura Grip for Dana 80, 4.10 and up.
| Brand | Eaton |
| Part number | 915A450 |
| Fits | Eaton Detroit Truetrac Differential 35 Spline 1.50in Axle Shaft Dia 4.10 & Up Ratio Rear Dana 80 |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Lower ratios normally take the 3.73-and-down case, but Eaton notes 915A450 will also fit OE 3.73 thin gear sets. Check whether your 3.73 set is the thin factory gear before you order.
Only if it has the Dana 80. Many Super Duty pickups used the Sterling 10.5 instead. Check the axle tag or send us your VIN.
No. Eaton specifies petroleum-mineral GL-5 80W-90 and says not to use synthetic oils or friction modifiers with this unit.
35-spline shafts. Eaton lists the shaft diameter as 1.52 inches.
A Truetrac needs some load on both tires to bias torque. If one tire is completely off the ground, lightly dragging the brakes helps it send power across.
Carrier bearings and races at minimum, and a full master overhaul kit if you are changing gears. Match the kit to your pinion race size.
