-8%
eaton_helical_gear
Eaton Detroit Truetrac differential full view
eaton_28_spline
Click to zoom in

Eaton Detroit Truetrac Differential 28 Spline 1.20in Axle Shaft Diameter Rear 9in

Eaton
EAT912A587
Differentials
3 Units In Stock - Ships Next Business Day
$ 745.65 $ 685.99
$ 685.99

SKU: 912A587

Eaton Detroit Truetrac Differential – 28 Spline, 1.20" Axle Shaft Diameter, Rear 9" (Ford)

The Eaton Detroit Truetrac Differential (912A587) is a helical-gear style, limited-slip differential designed for the Rear 9" Ford axle with 28 spline axles and 1.20" axle shaft diameter. It maximizes wheel traction by automatically transferring torque to the wheel with the most grip, improving acceleration, cornering, and overall driving performance. Unlike traditional clutch-type limited-slip differentials, the Truetrac is maintenance-free, operates smoothly in both forward and reverse, and requires no special fluids or additives. Its robust helical-gear design provides reliable, automatic operation without the chatter or engagement issues common with other limited-slip units. This makes the Detroit Truetrac an excellent choice for street, strip, or off-road applications where consistent traction and durability are essential.

Key Features

  • Helical-Gear Limited-Slip Design – Automatically transfers torque to the wheel with the most traction
  • Maintenance-Free Operation – No clutches to wear out, no special fluids required
  • Smooth & Quiet – Operates seamlessly in forward and reverse without chatter
  • 28 Spline, 1.20" Axle Shaft Diameter – Direct fit for Rear 9" Ford axles
  • Versatile Application – Ideal for street, performance, and off-road use

Specs

Spec Detail
Part Number 912A587
Brand Eaton Detroit Truetrac
Type Helical-Gear Limited-Slip Differential
Compatibility Rear 9" Ford axle with 28 spline axles and 1.20" axle shaft diameter
Spline Count 28
Axle Shaft Diameter 1.20 inches
Country of Origin United States
Warranty Eaton Limited Warranty

Whats Included

  • Detroit Truetrac Differential Assembly
  • Installation instructions

Product Notes

  • Designed for Rear 9" Ford axles with 28 spline axles and 1.20" shaft diameter
  • Provides automatic traction improvement without the maintenance of clutch-style units
  • Professional installation with proper setup and gear oil is highly recommended

Installation Notes

  • Requires differential disassembly and professional installation
  • Estimated time: Several hours (full differential rebuild recommended)
  • Use the correct limited-slip gear oil additive if specified by the vehicle manufacturer

This Part Fits

Year Range Make Model Notes
Various Ford Models with Rear 9" Axle 28 Spline, 1.20" Axle Shaft Diameter

Why Choose Eaton Detroit Truetrac Differentials?

  • Helical-gear design provides smooth, automatic traction without clutches or maintenance
  • Reliable performance in street, strip, and off-road applications
  • Trusted by enthusiasts and professional builders for decades

Frequently Asked Questions

  • Q: Is this differential a direct replacement for my stock unit?
    A: It is a direct drop-in for Rear 9" Ford axles with 28 spline axles and 1.20" shaft diameter, but professional installation and setup are required.
  • Q: Does it require special fluid?
    A: Use a high-quality limited-slip gear oil. Some applications may require an additive – check your vehicle’s specifications.
  • Q: Is professional installation required?
    A: Yes – differential work requires specialized tools, knowledge, and proper setup for safety and performance.

Shipping & Handling

  • Method: Ground UPS or FedEx (oversize shipping may apply)
  • Availability: In stock – ships same or next business day
  • Packaging: Secure Eaton retail packaging

Request For Information

Have questions about ? Fill out the form below and we'll get back to you by the next business day.
Differentials

Differentials

Differentials distribute engine torque between drive wheels, allowing them to rotate at different speeds through corners while maintaining traction. Upgrading from a factory open differential to a limited-slip or locking differential is one of the most impactful drivetrain improvements you can make for towing, off-roading, drag racing, or any application where both wheels need to work together under load.Popular Differential UpgradesTop upgrades include Eaton Detroit Locker and Eaton Truetrac limited-slip units for GM, Ford, Dana, and Chrysler axles, ARB Air Lockers for Jeep and truck off-road applications, and OS Giken Super Lock LSD units for JDM performance platforms. Locker conversions for Dana 44 and Dana 60 front axles are essential for serious rock crawling, while Truetrac helical LSDs deliver traction improvements without aggressive locking behavior for street and tow applications.What is the difference between a locker and a limited-slip differential?A locking differential ...

View Differentials Products
Differentials & Components

Differentials & Components

Shop differentials and components at Black Ops Auto Works for premium differentials, differential covers, differential gears, locker differentials, limited-slip differentials, install kits, rebuild kits, bushings, seals, yokes, spider gears, and final drive components for cars, trucks, SUVs, and off-road builds. Whether you are upgrading for better traction, stronger power delivery, improved durability, or drivetrain reliability, this collection includes the parts needed for street, towing, racing, and off-road applications. Shop Differentials & Components by Category Browse drivetrain and axle upgrades across popular product categories, including: Differentials Differential covers Differential cover gaskets Differential rebuild kits Differential install kits Differential overhaul kits Differential seal kits Differential bushings Differential mounts Differential braces Differential housings Differential dropouts Differential spider gears Differential yokes Final drive gears Wh...

View Differentials & Components Products
Drivetrain

Drivetrain

Shop drivetrain parts and accessories at Black Ops Auto Works for differentials, axles, driveshafts, clutch kits, flywheels, flexplates, shifters, transmission components, ring and pinion gears, differential braces, differential bushings, wheel hubs, wheel bearings, U-joints, valve bodies, transmission coolers, drivetrain mounts, and performance driveline upgrades. This collection is built for street cars, drag cars, track builds, trucks, Jeeps, SUVs, high-horsepower Mopar builds, imports, European performance vehicles, and off-road applications that need stronger power delivery, durability, and reliability. Use this Drivetrain collection to find the right upgrade by vehicle platform, drivetrain layout, transmission type, power level, and product category. Differentials and ring and pinion gears support traction and gearing changes, axles and driveshafts help transfer power, clutch kits and flywheels improve manual transmission performance, transmission coolers and valve bodies supp...

View Drivetrain Products
Eaton

Eaton

Eaton Performance is best known in the automotive aftermarket for its Eaton M90, M112, and M122 positive displacement supercharger roots-type blowers that power factory applications including the Ford Lightning, Mustang Cobra, Pontiac GTO, and Cadillac CTS-V as original equipment, which means the same engineering behind factory horsepower numbers reaches the enthusiast market directly through Eaton's performance division. The brand also produces Detroit Locker and Truetrac limited-slip and locking differentials that are among the most trusted traction management solutions for off-road, racing, and street-performance applications. Eaton's position as both an OEM supplier and a performance aftermarket brand gives its products an unusual combination of engineering rigor and enthusiast credibility. Builders who want proven, race-tested traction and boost solutions choose Eaton because the products have been validated at OEM production volumes before reaching aftermarket shelves.Popular ...

View Eaton Products
Military & First Responder Discounts

Military & First Responder Discount Program

Black Ops Auto Works proudly honors active duty military, veterans, National Guard, reserves, police officers, firefighters, and EMTs with an exclusive 5% discount on all performance parts and carbon fiber upgrades. Verify instantly and start saving today.

Learn More & Apply

Your cart

×