National 4278 Differential Pinion Seal - Rear Outer

National 4278 Differential Pinion Seal

National 4278 is a differential pinion seal built for rear axle service where a precise seal around the pinion shaft is critical. It uses fluoro-elastomer material and a Redicoat finish to help maintain sealing performance in demanding driveline conditions.

Key Features

• Part number 4278 differential pinion seal for rear outer axle applications
• Fluoro-elastomer construction for sealing durability
• Redicoat finish
• Inside diameter: 1.812 in. / 46.020 mm
• Outside diameter: 3.096 in. / 78.640 mm
• Flanged outside diameter: 3.400 in. / 86.360 mm
• Housing bore: 3.091 in. / 78.510 mm
• Thickness/width: 0.485 in. / 12.320 mm
• Series 4000, Type 86 oil seal

Product Details

National has supplied sealing solutions for more than 75 years, and this seal reflects that focus on fit and material selection. The 4278 is an oil seal used at the rear outer pinion area on a wide range of Ford, Lincoln, and related Visteon axle applications, including Ford F-150, Expedition, Mustang, Transit-150, Transit-250, Transit-350, F-250 Super Duty, and F-350 Super Duty platforms. This part cross-references SKF 18062A for the same application.

Common Problems This Seal Addresses

• Gear oil leakage at the rear outer pinion area
• Contamination entering the differential through a worn seal
• Noise or driveline issues caused by low lubricant level
• Seal wear from age, heat, and axle movement
• Service replacement on Ford and Lincoln rear axle assemblies

Installation Notes and Fitment

Fits 2019-2022 Ford F-150, rear outer.

Fits 2002-2018 Ford Expedition, rear outer, with 9.75 in ring gear; with Visteon axle; independent rear suspension.

Fits 2001-2018 Ford F-150, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2015-2018 Ford Mustang, rear outer, fits drive axle shaft bearing with 9.75 in ring gear, independent rear suspension, Visteon axle.

Fits 2015-2018 Ford Transit-150, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2015-2018 Ford Transit-250, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2015-2018 Ford Transit-350, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2015-2018 Ford Transit-350 HD, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2002-2018 Lincoln Navigator, rear outer, with 9.75 in ring gear; with Visteon axle; independent rear suspension.

Fits 2003-2011 Ford E-150, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2001-2010 Ford F-250 Super Duty, rear outer, with 10.5 in ring gear; with Visteon axle.

Fits 2001-2010 Ford F-350 Super Duty, rear outer, with 10.5 in ring gear; with Visteon axle.

Fits 2004-2008 Ford F-150, rear outer, with 10.25 in ring gear; with Visteon axle.

Fits 2006-2008 Lincoln Mark LT, rear outer, with 9.75 in ring gear; with Visteon axle; independent rear suspension.

Fits 2003-2005 Ford E-150 Club Wagon, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2001-2005 Ford Excursion, rear outer, with 10.5 in ring gear; with Visteon axle.

Fits 2004 Ford F-150 Heritage, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2001-2002 Ford E-150 Econoline, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2001-2002 Ford E-150 Econoline Club Wagon, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2002 Lincoln Blackwood, rear outer, with 9.75 in ring gear; with Visteon axle; independent rear suspension.

Fits 2001 Ford Expedition, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2001 Lincoln Navigator, rear outer, with 9.75 in ring gear; with Visteon axle.

Fits 2000 Ford E-150 Econoline, rear outer, fits vehicles with 9.75 in ring gear and Ford axle.

Fits 2000 Ford E-150 Econoline Club Wagon, rear outer, fits vehicles with 9.75 in ring gear and Ford axle.

Fits 2000 Ford Excursion, rear outer, with 10.5 in ring gear; with Ford axle.

Fits 2000 Ford Expedition, rear outer, fits vehicles with 9.75 in ring gear and Ford axle.

Fits 2000 Ford F-150, rear outer, fits vehicles with 9.75 in ring gear and Ford axle.

Fits 1999-2000 Ford F-250 Super Duty, rear outer, with 10.5 in ring gear; with Ford axle.

Fits 1999-2000 Ford F-350 Super Duty, rear outer, with 10.5 in ring gear; with Ford axle.

Fits 2000 Lincoln Navigator, rear outer, fits vehicles with 9.75 in ring gear and Ford axle.

Fits 1999 Ford E-150 Econoline, rear outer, 2nd design; with 9.75 in ring gear; with 0.485 in width; with Ford axle; 3.09 in outside diameter.

Fits 1999 Ford E-150 Econoline Club Wagon, rear outer, 2nd design; with 9.75 in ring gear; with 0.485 in width; with Ford axle; 3.09 in outside diameter.

Fits 1999 Ford Expedition, rear outer, 2nd design; with 9.75 in ring gear; with 0.485 in width; with Ford axle; 3.09 in outside diameter.

Fits 1999 Ford F-150, rear outer, 2nd design; with 9.75 in ring gear; with 0.485 in width; with Ford axle; 3.09 in outside diameter.

Fits 1985-1999 Ford F-250, rear outer, with 10.25 in ring gear; with Ford axle.

Fits 1999 Lincoln Navigator, rear outer, 2nd design; with 9.75 in ring gear; with 0.485 in width; with Ford axle; 3.09 in outside diameter.

Fits 1985-1998 Ford F-350, rear outer, with 10.25 in ring gear; with Ford axle.

Quality Assurance

National is known for premium sealing solutions and ongoing design support for modern vehicle applications. Part number 4278 is built to match the dimensional requirements listed for the specified rear axle service applications.