Zumbrota Drivetrain RAA440-1383B Remanufactured Rear Axle Assembly Ford 9.75" IRS 3.73 Ratio

The Zumbrota Drivetrain RAA440-1383B is a remanufactured complete rear axle assembly built for the Ford 9.75-inch Independent Rear Suspension (IRS) differential with a 3.73 gear ratio. Also referenced as Zumbrota part 440-01383B, this unit is engineered to restore OEM drivetrain performance with the precision and reliability of a professionally remanufactured component.

The Ford 9.75-inch rear axle is a heavy-duty unit featuring a 9.75-inch ring gear and 34-spline axle shafts, originally designed as a higher-capacity alternative to the Ford 8.8-inch differential. This IRS variant is built to handle the demands of full-size SUV towing and hauling applications.

Zumbrota Remanufacturing Process:

• Exclusive hydro-blast rinse and sandblasting procedure on all internal and external components, restoring housings to OEM finish
• 100% inspection of all internal parts including ring & pinions, internal gears, clutches, and carriers
• 100% replacement of bearings, seals, crush sleeves, pinion nuts, and shims
• All housings tested for surface wear and cracks
• Axle tubes inspected and straightened to OEM specifications
• Gear tooth contact patterns fully verified for optimal engagement
• Correct rolling torque established using inch-pound measurements for precision setup and long-term durability
• Correct gear backlash set to ensure proper lubrication and quiet operation
• Units shipped in high-density plastic totes to eliminate in-transit damage

This axle assembly is a direct-fit replacement unit built to stringent quality standards, providing a reliable solution for restoring proper drivetrain function without the cost or lead time of sourcing a new OEM assembly.