Eaton Detroit Truetrac Differential 30 Spline 1.31in Axle Shaft Dia 3.92 & Up Ratio Front Dana 44
Most four-wheel drives with a front Dana 44 still run an open front carrier, which means that in 4WD the front axle quits pulling the moment one front tire finds ice, mud or air. Plow trucks, Scouts, older Ford and Dodge 4x4s and solid-axle swap builds are where people notice it. The Eaton Detroit Truetrac 913A592 turns that front axle into a helical-gear limited slip for a Dana 44 front with 30-spline, 1.31 inch inner shafts, an 8.5 inch ring gear and ratios of 3.92 and numerically higher.
Up front, the Truetrac only has work to do when the transfer case is in 4WD. With the hubs unlocked or the front driveshaft idle, the carrier just turns along like an open differential. Engaged in 4WD, its parallel helical gears sit in pockets in the case; when one front tire starts to spin, the gears push against those pockets and the friction sends torque to the tire that still has grip. There are no clutch plates or springs to wear out, which is why it is a common pick for a front axle that sees snow work and trail use. A helical unit is gentler on steering than a full locker, but you may still feel more tug at the wheel on throttle in tight 4WD turns than with the open carrier.
First, make sure your front axle is a Dana 44 and not a Dana 30; our Dana 30 vs Dana 44 front axle guide shows how to tell them apart by ring gear size and cover shape. Then count the inner shaft splines and read the ratio from the axle tag or by counting driveshaft turns per wheel turn. The Dana 44 carrier break is between 3.73 and 3.92, and this unit is for 3.92 and up. Eaton's catalog heading for 913A592 reads 3.73 and up while its spec field says 3.92 and up; the listing and our distributor's spec block both say 3.92 and up, so if your front axle has 3.73 gears, send us the ratio before you order. The Dana 44 problems guide covers the bearing and seal wear worth checking while you are in there.
Eaton's application notes for 913A592 list front Dana 44s in Ford half-ton and three-quarter-ton trucks, Chrysler, Dodge, Ram and Plymouth trucks, and 1967-1980 International Harvester pickups and Scouts, without year rows for most of them. The key catalog note: it applies to non-axle-disconnect housings only. Dana 44 fronts that use a center axle disconnect (vacuum or cable shift that splits one axle shaft at the tube) are not a fit. Dana 44s were built with several spline counts over the years, so count yours. Match axle, spline count, ratio and disconnect type, or send us the year and VIN. For the rear axle, order the rear Dana 44 Truetrac; if you want a selectable full locker up front instead, compare the ELocker4 for the Dana 44 front. More axle parts are in hard parts.
Pull the hubs or axle shafts first, then the carrier. Transfer the ring gear with new bolts and thread locker, fit carrier bearings (new is cheap insurance), and start with the original shim pack; check backlash and pattern before the cover goes on. Use a Dana 44 carrier shim driver to seat the shims without damaging them, and replace the inner axle seals with a front axle seal installer so they go in square, since a leaking inner seal puts gear oil in the knuckles. Fill with GL-5 gear oil; the guidance on the distributor listing is mineral GL-5, synthetic if the axle maker approves, and no friction modifier. Our Truetrac buyer's guide covers more about matching splines and ratios.
| Brand | Eaton |
| Part number | 913A592 |
| Fits | Eaton Detroit Truetrac Differential 30 Spline 1.31in Axle Shaft Dia 3.92 & Up Ratio Front Dana 44 |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. Eaton's catalog note says it applies to non-axle-disconnect housings only. Fronts with a vacuum or cable center disconnect are not a fit for this unit.
Order by the carrier break. The listing and spec say 3.92 and up, and Dana 44 ratios from 3.73 down use the smaller carrier. Send us your ratio and axle tag before ordering if you have 3.73 gears.
Only in 4WD. With hubs unlocked or the transfer case in 2WD the front axle is not driving and the carrier just turns. In 4WD you may feel some extra pull on throttle in tight turns, much less than with a full locker.
Order the part Eaton catalogs for your axle position. Eaton lists 913A592 for the front Dana 44 and 913A590 for the rear at 3.92 and up.
A GL-5 gear oil, mineral based or synthetic if your axle maker approves it. Do not add friction modifier; the Truetrac has no clutch plates and the additive reduces its torque bias.
Carrier bearings, inner axle seals, the pinion seal and the cover gasket. If you are also regearing, do the pinion bearings and a new crush sleeve or solid spacer.
