Eaton 915A567 Detroit TrueTrac LSD for Dana 80 Rear 35-Spline 3.73 & Down Ratio

Vehicle Fitment

• 1994-2002 Chrysler / Dodge / Ram / Plymouth Three-Quarter-Ton and One-Ton Truck, Wagon, Van, Cab & Chassis, Motor Home (Dana 80 Rear, 35-Spline, 3.73 & Numerically Lower)
• 1998-2016 Ford One-Ton Truck, Van, Wagon, Cab & Chassis (Dana 80 Rear, 35-Spline, 3.73 & Numerically Lower)

Fitment Notes

• Fits the Dana 80 rear axle only - confirm your axle is a Dana 80 before ordering; this unit does not fit any other axle type
• Requires a ring and pinion gear ratio of 3.73 or numerically lower (e.g., 3.55, 3.31, 3.07) - this differential is NOT compatible with gear ratios higher than 3.73 (e.g., 4.10, 4.56); for 4.10 & up Dana 80 applications, see Eaton 915A450
• Ford 3.73 caution: some factory Ford 3.73 ring gears were machined thinner than standard to fit on the 4-series carrier - verify that your 3.73 ring gear is standard thickness before installing this unit
• 35-spline axle shaft configuration - confirm your Dana 80 axle shaft spline count before ordering
• Axle shaft diameter: 1.52 in.; Ring gear size: 11.5 in.
• Rear axle application only
• Lubrication: Eaton requires petroleum/mineral-based GL-5 80W90 gear oil for all TrueTrac differentials - do NOT use synthetic gear oil or friction modifier additives
• Sold as an individual differential unit - installation kit (bearings, shims, seals, pinion seal, crush sleeve, ring gear bolts, and cover gasket) sold separately; see compatible Eaton master install kits K-D80-98.5R (1998.5 & newer) and K-D80-R (1998 & older)
• Installation instructions available for download via Eaton's product page

Features

• Detroit TrueTrac - Eaton's helical-gear limited-slip differential, using a patented parallel-axis planetary helix gear design to automatically and smoothly transfer torque to the wheel with better traction without friction discs, clutches, or driver input
• Clutchless design - no friction clutch packs, no wearable internal components; the TrueTrac's torque bias is generated entirely through gear geometry, making it completely maintenance-free for the life of the unit
• Fully automatic torque biasing - senses wheel speed differentiation and redistributes torque from the slipping wheel to the gripping wheel automatically, with no switches, solenoids, electronics, or driver action required at any time
• Smooth, progressive engagement - unlike a full locker, the TrueTrac transitions between open-differential behavior and torque transfer gradually, providing traction improvement without the wheel hop, clunking, or understeer associated with automatic locking differentials during on-road use
• Functions identically in forward and reverse - gear-driven torque biasing is direction-independent, providing traction improvement under all driving conditions
• Optimized torque bias ratios - helical gear geometry engineered to maximize torque transfer under wheel slip conditions while allowing smooth cornering behavior on paved roads
• Quiet, durable operation - produces no ratcheting, clicking, or mechanical noise during normal on-road driving; behaves identically to an open differential in everyday use
• Product weight: 54.49 lbs; Ring gear size: 11.5 in.; Axle shaft diameter: 1.52 in.; 35-spline interface
• Suitable for street and muscle, towing, circle track, drag racing, restoration, light trail, rock crawl, and extreme off-road applications per Eaton's vehicle usage classifications

Specifications

• Part Number: 915A567
• Product Type: Detroit TrueTrac Helical-Gear Limited-Slip Differential
• Axle Application: Dana 80 - Rear
• Axle Shaft Spline Count: 35
• Axle Shaft Diameter: 1.52 in.
• Ring Gear Size: 11.5 in.
• Ring Gear Ratio Requirement: 3.73 & Numerically Lower
• Differential Type: Helical-Gear Limited Slip (Clutchless, Automatic Torque Biasing)
• Operation: Fully Automatic (no driver input required)
• Lubrication: Petroleum/Mineral-Based GL-5 80W90 Gear Oil Only - No Synthetic, No Friction Modifier
• Product Weight: 54.49 lbs
• Quantity: Sold Individually (installation kit not included)

Included Components

• 1x Eaton Detroit TrueTrac Differential Unit (915A567)
• Note: Bearings, shims, pinion seal, crush sleeve, ring gear bolts, and differential cover gasket are NOT included - order the appropriate Eaton master installation kit separately: K-D80-98.5R for 1998.5 & newer applications, or K-D80-R for 1998 & older applications

Product Description

The Eaton 915A567 is a Detroit TrueTrac helical-gear limited-slip differential for the Dana 80 rear axle, designed for 35-spline applications running gear ratios of 3.73 or numerically lower. It covers 1994-2002 Chrysler, Dodge, Ram, and Plymouth three-quarter-ton and one-ton trucks, vans, wagons, cab and chassis, and motor homes, and 1998-2016 Ford one-ton trucks, vans, wagons, and cab and chassis vehicles equipped with the Dana 80 rear axle.

The TrueTrac uses Eaton's patented parallel-axis planetary helix gear arrangement to generate torque bias entirely through gear geometry - not friction. When one rear wheel begins to slip, the internal helical gear set produces an axial force proportional to the torque load, automatically redirecting drive torque to the wheel with traction. This happens smoothly and progressively with no driver intervention required. There are no clutch packs to wear, no adjustment intervals, and no electronics to service - the TrueTrac is maintenance-free for the life of the differential. On paved roads it operates silently and indistinguishably from an open differential, engaging smoothly as traction conditions demand. It works equally in forward and reverse, making it well-suited to the towing, hauling, and varied-terrain applications common to the Dana 80-equipped heavy-duty platforms it covers.

Ford 3.73 buyers should note that some factory Ford 3.73 ring gears were machined to a thinner-than-standard profile to fit on the 4-series carrier - verify your ring gear thickness is standard before installing this unit, as the 915A567 is designed for standard-thickness 3 series carrier ring gears. Eaton requires petroleum/mineral-based GL-5 80W90 gear oil; synthetic oil and friction modifier additives must not be used. The 915A567 is sold as a differential unit only - installation hardware must be ordered separately via the appropriate Eaton master install kit. Application guide and installation instructions are available for download through Eaton's website.