Eaton Detroit Truetrac Differential 35 Spline 1.50in Axle Shaft Diameter 4.56 & Up Ratio Dana 60HD
A 35-spline Dana 60 front axle on a Ford Super Duty, a Dodge or Ram three-quarter or one-ton, or an older GM one-ton is usually geared deep once the truck is lifted and on bigger tires. The Eaton Detroit Truetrac 915A388 is the gear-driven limited slip built for that case: Dana 60 front, 35-spline axle shafts with a 1.50 inch diameter, and ring and pinion ratios of 4.56 and numerically higher. If your front end drags a spinning tire up loose climbs, or you want traction up front without the steering fight of a full locker, this is the carrier people search for.
The Truetrac has no clutch packs, springs or air lines. Inside the case, sets of parallel-axis helical pinion gears mesh with the side gears. When one tire starts to lose grip, the gear separating loads make the pinions bite against their pockets, and that friction sends more torque to the tire that still has traction. On pavement the unit acts close to an open differential, so a front axle with a Truetrac still steers predictably when the hubs are locked. It works in either rotation direction, which matters because many Dana 60 fronts are reverse-rotation high-pinion axles. Eaton rates the ring gear size at 9.75 inches and the unit weight at 45 lb, and the catalog note says it is for non-thick ring gears only.
Three things decide fitment: the axle is a front Dana 60, the inner shafts are 35-spline, and the ring and pinion is 4.56 or deeper. The carrier break on a Dana 60 falls between 4.10 and 4.56, so a 4.10 truck needs a different case. Our carrier break guide shows how to read the ratio off the ring gear, and the Dana 60 front axle problems guide covers the bearing and joint wear to fix during the same job. If you are still choosing between a locker and a limited slip, read Detroit Locker vs Truetrac.
Eaton's product selector lists this part for the front Dana 60 in 1979-2020 Ford three-quarter and one-ton trucks, vans and SUVs, 1976-2000 Dodge and Ram three-quarter and one-ton trucks, 1971-1993 Dodge half-ton and smaller applications, 1975-1991 GM three-quarter-ton trucks and 1977-1987 GM one-ton trucks, all at 4.56 and up. Not every truck in those years came with a Dana 60 up front, and some used 30-spline shafts, so confirm the axle tag and spline count or send us your year and VIN. Do not use it with thick ring gears. If you need the rear-axle version of this carrier, look at the Truetrac 915A386 rear Dana 60, and for a selectable front option compare the ELocker4 14023-010. More carriers are in our hard parts category.
Pull the axle shafts far enough to clear the carrier, mark the bearing caps, and spread the housing slightly before lifting the case out. Move the ring gear to the Truetrac with clean threads and new ring gear bolts, then press on new carrier bearings. The Yukon Dana 60/61 front master overhaul kit or the Revolution Koyo master install kit supplies the bearings, shims and seals. Set carrier preload and check backlash and the contact pattern, because a new case can shift the ring gear position. Refill with a quality GL-5 gear oil in 75W-90 or 75W-140; the Truetrac has no clutches and needs no friction modifier. Avoid long one-wheel-in-the-air spinning, since a lifted tire carries no load for the gears to work against; light brake pressure helps it transfer torque.
| Brand | Eaton |
| Part number | 915A388 |
| Fits | Eaton Detroit Truetrac Differential 35 Spline 1.50in Axle Shaft Diameter 4.56 & Up Ratio Dana 60HD |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. This case is built for 4.56 and numerically higher ratios. A Dana 60 with 4.10 or lower gears uses the 4.10-and-down carrier, because the ring gear sits at a different height on each side of the carrier break.
Eaton's selector lists the 915A388 for front Dana 60 applications on Ford, Dodge and GM trucks. For a rear Dana 60 with 35-spline shafts and 4.56-up gears, use the 915A386 rear version.
No. Eaton's catalog note for this part says it is for non-thick ring gears only. If you are running a thick gear set, pick a carrier listed for thick gears before ordering.
No. It is an all-gear limited slip with no clutch packs, so a straight GL-5 gear oil in the correct viscosity is all it needs.
New carrier bearings and races, ring gear bolts, and the shims needed to set preload and backlash. A master overhaul or master install kit for the Dana 60 covers those parts in one box.
Much less than a full locker. The Truetrac only biases torque when one tire slips, so with the hubs locked it still lets the front wheels turn at different speeds through corners.
