National 370018A Wheel Seal - Rear Inner

National 370018A Wheel Seal for Ford F-350 Super Duty

National 370018A is an oil bath wheel seal built for the rear inner position on Ford F-350 Super Duty applications. It uses nitrile sealing material and Redicoat protection to support consistent sealing performance in driveline and axle service.

With a 4.506-inch outside diameter, 4.500-inch housing bore, and 3.250-inch shaft diameter, this seal is specified for precise axle and hub dimensions. The National 370018A wheel seal is a direct-fit option for 1999-2021 Ford F-350 Super Duty rear inner service.

Key Features

• Wheel seal for driveline and axle sealing applications
• Fits 1999-2021 Ford F-350 Super Duty, rear inner
• Nitrile sealing material for oil bath service
• Redicoat surface treatment
• 4.506 in. outside diameter and 4.500 in. housing bore
• 3.250 in. shaft diameter specification
• National 370018A / 370018A replacement reference

Detailed Description

National 370018A is part of National’s 370000 series and is engineered as an oil bath seal for axle and hub sealing needs. The seal’s dimensions include a 0.605-inch width, 114.450 mm outside diameter, and 114.300 mm housing bore, helping it match the required fitment for the rear inner wheel seal location on Ford F-350 Super Duty trucks. This part cross-references Timken 10S32500 for the same application.

National has focused on sealing solutions for more than 75 years, and this wheel seal reflects that experience with a design intended for modern vehicle service requirements. If you are replacing a rear inner wheel seal on a Ford F-350 Super Duty, National 370018A provides the specified dimensions and material construction needed for the job.

What This Wheel Seal Helps Address

• Gear oil leakage at the rear inner wheel seal area
• Contamination entering the hub or axle sealing surface
• Seal wear from heat, road debris, and mileage
• Loss of proper oil bath retention in axle service
• Noise or service issues related to a worn wheel seal

Installation Notes and Tips

Verify the housing bore, shaft diameter, and seal width before installation to confirm the seal matches the axle assembly. Use the specified installation tool RD275 when servicing this seal, and inspect the axle ring designation AR8 during replacement. Clean the sealing surfaces thoroughly and check the hub and axle components for wear before installing the new seal.

Fits 1999-2021 Ford F-350 Super Duty, rear inner.

Quality Assurance

National is a long-established sealing brand with a reputation built over decades in the aftermarket. The 370018A is manufactured as a precision wheel seal for oil bath applications and is backed by National’s sealing expertise.