National 4503N Transfer Case Output Shaft Seal - Rear

Transfer Case Output Shaft Seal for 4WD Applications

The National 4503N transfer case output shaft seal is built for rear transfer case sealing on a wide range of Ford, Chevrolet, GMC, Cadillac, Lincoln, Ram, Hummer, and Oldsmobile 4WD applications. It uses a polyacrylate sealing material and a bi-directional lip design to help maintain a consistent seal at the output shaft.

National has supplied sealing solutions for more than 75 years, and this oil seal is part of the 4000 series. The 4503N measures 1.886 inches inside diameter, 2.765 inches outside diameter, and 0.469 inch width, with a flanged outside diameter of 3.270 inches and a housing bore of 2.750 inches.

Key Features

• Transfer case output shaft seal for rear applications
• Polyacrylate sealing material for sealing performance
• Bi-directional lip design
• National 4000 series oil seal
• Dimensions: 1.886 in ID, 2.765 in OD, 0.469 in width
• Flanged outside diameter: 3.270 in
• Housing bore: 2.750 in

Detailed Description

National 4503N is a transfer case output shaft seal designed for vehicles using Borg-Warner transfer cases across part-time and full-time 4WD systems. It is listed for applications such as the 2015-2019 Chevrolet Colorado, 2015-2019 GMC Canyon, 2007-2014 Ford F-150, 2007-2014 Chevrolet Tahoe, and 2011-2019 Ram 1500 rear transfer case positions, along with many additional Ford Expedition, Lincoln Navigator, GMC Sierra 1500, Chevrolet Silverado 1500, and Hummer models.

This part cross-references Gates 18507 and Febi-Bilstein 18687 for the same application. The National 4503N part number is also used as the primary reference for this seal.

What This Seal Helps Address

• Transfer case fluid seepage at the output shaft
• Oil leakage around the rear transfer case seal area
• Contamination from worn or hardened sealing lips
• Loss of sealing integrity in high-mileage 4WD drivetrains
• Service replacement for worn Borg-Warner transfer case seals

Installation Notes and Tips

Verify the transfer case model, shaft diameter, housing bore, and seal dimensions before installation. This seal is listed for rear positions and multiple Borg-Warner transfer case variants, so matching the exact vehicle configuration is important. Inspect the output shaft surface for wear, scoring, or corrosion before installing the new seal, and confirm the seal seats evenly in the bore.

Quality Assurance

National backs this seal with more than 75 years of sealing-system experience and a design approach focused on current vehicle requirements. The 4503N is engineered as a precision oil seal for transfer case service and dimensional fitment across the listed applications.