Eaton Detroit Truetrac Differential 30 Spline 1.31in Axle Shaft Dia 3.73 & Down Ratio Rear Dana 44
A Jeep Wrangler TJ, YJ or CJ with the rear Dana 44 that spins the inside tire climbing a washed-out trail, a non-Rubicon JK whose rear open diff lets one wheel dig, or an older Scout or Ford half-ton with a 30-spline Dana 44 rear: the Eaton Detroit Truetrac 913A589 gives that axle automatic traction without changing how the vehicle drives on pavement. It is the rear Dana 44 Truetrac for 30-spline, 1.31 inch shafts with ring gear ratios of 3.73 and numerically lower.
Inside the case are two sets of helical pinions meshed with the side gears. As long as both tires grip, it acts like an open differential and lets them turn at different speeds through a corner. When one tire starts to lose grip, the load on those helical gears forces them against the walls of their pockets, and that friction transfers torque to the tire with traction. Nothing has to be switched on, there are no clutches to glaze, and it works going forward and backing down a ledge. Because it reacts to torque, lightly holding the brake while you apply throttle helps when one tire is fully in the air.
Start with the axle tag on the cover bolts and the ring gear ratio. This part is for 3.73 and numerically lower gears on non-thick ring gears; a 3.92 or deeper gear set sits on a different carrier, which is the 3.92-and-up 30-spline Truetrac. If you plan to regear to 4.10 or 4.56 for bigger tires, buy the carrier for the new ratio, not the old one. Then count the splines on an axle shaft. Our Dana 44 problems and rebuild guide and the carrier break guide explain both checks.
Eaton's selector and Quadratec's fitment notes list 913A589 for the rear Dana 44 in 1976-1986 Jeep CJ-7, 1981-1985 CJ-8, Wrangler YJ, and 1997-2006 Wrangler TJ with 3.73 and lower ratios, plus the 2007-2018 Wrangler JK non-Rubicon rear in all ratios. Eaton also lists 1967-1980 International Harvester Scout and pickups, 1977-1979 Ford half-ton trucks and vans with a rear Dana 44, and 1993-2000 Isuzu Rodeo. It does not fit Rubicon models. Dana 44 builds varied, especially in older Jeeps and swapped axles, so match the axle tag and spline count, or send us your year and VIN. More axle parts are in the hard parts section.
| Brand | Eaton |
| Part number | 913A589 |
| Fits | Eaton Detroit Truetrac Differential 30 Spline 1.31in Axle Shaft Dia 3.73 & Down Ratio Rear Dana 44 |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. Rubicon models are not covered. This unit is for the non-Rubicon rear Dana 44.
This one is for 3.73 and numerically lower gears. A 3.92 or deeper ratio uses the 3.92-and-up rear Dana 44 Truetrac.
Yes. Eaton and Quadratec list the 2007-2018 JK non-Rubicon rear for all ratios, but the carrier flange must be drilled to 1/2 inch to match the factory JK ring gear bolts.
No. The Truetrac uses helical gears, not clutches, so standard GL-5 gear oil is correct.
No. Eaton specifies non-thick ring gears only for this carrier.
A rear Dana 44 master overhaul or bearing kit, new ring gear bolts, gear oil and a cover gasket. If you are regearing, buy the ring and pinion at the same time.
