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National 100727 Differential Pinion Seal - Rear Outer
| Brand | National 100727 |
|---|---|
| Position | Rear Outer |
| Flanged Outside Diameter (Inch) | 4.331 |
| Flanged Outside Diameter (MM) | 110.000 |
| Housing Bore (Inch) | 4.035 |
| Housing Bore (MM) | 102.490 |
| Inside Diameter | 2.500 |
| Inside Diameter | 63.500 |
| Material | Fluoro-Elastomer |
| Outside Diameter | 4.042 |
| Outside Diameter | 102.670 |
| Outside Diameter (Inch) | 4.042 |
| Outside Diameter (mm) | 102.670 |
| Overall Width with Side Lip (MM) | 0.630 |
| Overall Width with Side Lip (Inch) | 16.000 |
| Part Description | Oil Seal |
| Series | 100000 |
| Shaft (Inch) | 2.500 |
| Shaft (MM) | 63.500 |
| Thickness | 0.492 |
| Thickness | 12.500 |
| Type | 74 |
| Unit of Dimension | Inch |
| Width (Inch) | 0.492 |
| Width (mm) | 12.500 |
| Fits | GMC, Chevrolet, and Dodge · 13 vehicles |
Fluoro-elastomer seal. Resists heat and wear for dependable sealing performance.
Oil seal design. Helps keep lubricant contained where it belongs.
Premium sealing solutions. Backed by more than 75 years of National expertise.
Cross-references Eastern Catalytic 50563, National 100727 and SKF 25056 for the same application. See all 13.
National 100727 Differential Pinion Seal
National 100727 is a differential pinion seal built for rear axle service where precise sealing matters. It uses fluoro-elastomer construction and OE-style dimensions to help maintain a tight seal at the pinion shaft on select Dodge Ram, Chevrolet Silverado 3500, and GMC Sierra 3500 applications.
Key Features
- Part number: National 100727
- Part description: oil seal for differential pinion service
- Fluoro-elastomer material for sealing performance in driveline applications
- Inside diameter: 2.500 in. / 63.500 mm
- Outside diameter: 4.042 in. / 102.670 mm
- Flanged outside diameter: 4.331 in. / 110.000 mm
- Housing bore: 4.035 in. / 102.490 mm
- Width: 0.492 in. / 12.500 mm
- Overall width with side lip: 0.630 in. / 16.000 mm
- Series 100000, Type 74
Detailed Description
This differential pinion seal is engineered around the listed shaft and housing dimensions to support a proper fit at the rear outer pinion location. National has supplied sealing solutions for more than 75 years, and this part reflects that focus with a design intended for modern driveline sealing demands. National 100727 is a direct-fit style replacement for vehicles that require the specified 11 mm ring gear and Spicer 80 axle configuration, including 2001-2002 Dodge Ram 2500, 2001-2002 Dodge Ram 3500, 2003-2006 Chevrolet Silverado 3500, 2003-2006 GMC Sierra 3500, and 2007 GMC Sierra 3500 Classic.
This part cross-references SKF 25056 for the same application.
What This Seal Helps Address
- Gear oil seepage at the differential pinion area
- Fluid loss from a worn or hardened pinion seal
- Contamination around the rear axle pinion shaft
- Noise or driveline issues caused by low differential lubricant level
- Service replacement needs on rear outer pinion seal applications
Installation Notes and Tips
Verify axle configuration before ordering. This seal is listed for rear outer applications with an 11 mm ring gear and Spicer 80 axle, and fitment varies by year and model. Confirm the shaft diameter, housing bore, and seal width against the original part before installation. Clean the sealing surface and inspect the pinion yoke for wear or grooves that could affect sealing performance. For fitment reference, this part fits 2001-2002 Dodge Ram 2500, rear outer; fits 2001-2002 Dodge Ram 3500, rear outer; fits 2003-2006 Chevrolet Silverado 3500, rear outer; fits 2003-2006 GMC Sierra 3500, rear outer; and fits 2007 GMC Sierra 3500 Classic, rear outer.
Quality Assurance
National is a long-established sealing brand with a reputation built on premium sealing solutions and ongoing product development for current vehicle needs. National 100727 is manufactured to support consistent differential sealing performance in the specified driveline applications.
| Year | Make | Model | Position | Notes |
|---|---|---|---|---|
| 2007 | GMC | Sierra 3500 Classic | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2006 | Chevrolet | Silverado 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2006 | GMC | Sierra 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2005 | Chevrolet | Silverado 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2005 | GMC | Sierra 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2004 | Chevrolet | Silverado 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2004 | GMC | Sierra 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2003 | Chevrolet | Silverado 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2003 | GMC | Sierra 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2002 | Dodge | Ram 2500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2002 | Dodge | Ram 3500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2001 | Dodge | Ram 2500 | Rear Outer | Fits with 11mm Ring Gear and Spicer 80 Axle |
| 2001 | Dodge | Ram 3500 | Rear Outer | 2nd Design; with 11 (mm) Ring Gear; with Spicer 80 Axle |
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