Eaton Detroit Truetrac Differential 30 Spline 1.31in Axle Shaft Dia 4.10 & Down Ratio Rear...

Older Dodge D- and W-series pickups, 1970s and early-1980s Ford F-250s, some GM three-quarter tons before the 14-bolt, and the lighter-duty 1994-2002 Ram 2500 all came with a Dana 60 rear axle, and many of them have the 30-spline shafts. If yours spins one tire on a slick ramp or a snowy driveway, or the old Powr-Lok has gone flat, the Eaton Detroit Truetrac 913A389 is a drop-in limited slip for a Dana 60 rear with 30-spline, 1.31 inch axle shafts and gears of 4.10 or numerically lower.

What the Truetrac does in a Dana 60 rear

The Truetrac is a helical-gear limited slip. Instead of a clutch pack, it uses parallel helical pinions sitting in pockets in the case. In normal driving it acts like an open differential, so it is quiet and smooth in turns. When one tire starts to lose grip, the helical gears push against their pockets with more force and that friction sends torque to the tire that still has traction. Eaton's own description stresses that it engages automatically, works in forward and reverse, has no wearing clutch parts and needs no maintenance. For a work truck or a tow rig that matters: there are no clutches to wear thin and no friction modifier to forget at the next oil change.

Symptoms that point to a Truetrac

• One-wheel spin on wet pavement, gravel or snow, especially when pulling a trailer
• A Powr-Lok or other clutch-type limited slip that chatters in turns or no longer holds
• Worn spider gears or side gears with a clunk on and off throttle
• A regear or bearing job where the carrier is coming out anyway

How to confirm before ordering

Three things must match: the axle, the spline count and the carrier break. Read the axle tag for the Dana 60 and ratio, then pull a shaft and count splines; semi-float Dana 60 rears are almost always 30 spline. The carrier break is the part people miss. Dana 60 ratios through 4.10 use one carrier and 4.56-and-deeper gears use another, so this unit is for 4.10-down gears, or for a deep ratio cut as a thick gear set. Our Dana 60 rear axle guide covers telling a 60 from a 61 or a Dana 70, and the carrier break explainer shows why the ratio decides which case you order.

Fitment

Per the listing and Revolution's spec block: Dana 60 rear, 30-spline axles at 1.31 inch shaft diameter, 4.10 and down carrier break. It does not list vehicles by year, because Dana 60 rears ran under many trucks. Match the axle tag, spline count and current ratio, or send us year and VIN. A 35-spline full-floater takes a different Truetrac, such as the 35-spline 4.10-down version, and a 4.56-and-up axle needs the 4.56-up carrier. Browse more axle parts in the hard parts collection.

Install notes

• The Dana 60 carrier is preloaded into the housing with shims. Use a Dana 60 housing spreader to remove and refit it, and spread no further than needed.
• Move the ring gear to the new case with new bolts and thread locker. Install new carrier bearings and keep the shim packs side for side as a starting point.
• Verify backlash and contact pattern before closing it up. A new case can shift the pattern slightly.
• Going deeper on gears? A thick set such as the Yukon Dana 60 4.88 thick gear set is made to fit this 4.10-down carrier. Replace the bearings with a Dana 60/61 rear master overhaul kit.
• Fill with a GL-5 gear oil. Eaton recommends against friction modifier because it reduces Truetrac performance.

For trails with a tire off the ground, a light left-foot brake drag adds resistance at the spinning wheel and helps the Truetrac send torque across. See the Truetrac buyer's guide for more.

Will 913A389 work with 4.56 or 4.88 gears?

Only with a thick gear set made for the 4.10-down carrier. Standard 4.56-and-deeper Dana 60 gears need the 4.56-and-up Truetrac instead.

My Dana 60 has 35-spline shafts. Is this the right one?

No. This unit is machined for 30-spline, 1.31 in. shafts. A 35-spline full-floater needs a 35-spline Truetrac for your ratio range.

Do I need friction modifier?

No. Eaton states friction modifiers should not be used with the Truetrac because they reduce its performance. Use a quality GL-5 gear oil.

Does the Truetrac wear out like a clutch limited slip?

It has no clutch packs or springs, and Eaton describes it as maintenance free. Bearings and gears still wear normally, so service those on schedule.

What should I replace while it is apart?

New carrier bearings and races, ring gear bolts, a cover gasket and the pinion seal. If the pinion bearings are rough, a Dana 60/61 rear master overhaul kit covers everything.