National 5778 Differential Pinion Seal - Front Outer or Rear Outer

National 5778 Differential Pinion Seal Overview

The National 5778 differential pinion seal is engineered to provide reliable sealing performance for a range of vehicles including Chevrolet, Ford, Dodge, and Jeep models. Designed with precision dimensions and durable polyacrylate material, this oil seal helps maintain proper lubrication and prevent leaks in driveline systems.

• Inside diameter: 1.552 inches (39.420 mm)
• Outside diameter: 3.165 inches (80.390 mm)
• Thickness/width: 0.645 inches (16.383 mm)
• Material: Polyacrylate for enhanced durability
• Redicoat surface treatment for corrosion resistance
• Series 5000, Type 72 design for consistent fit and function

Technical Details and Specifications

This National differential pinion seal (part number 5778) features an inside diameter of 1.552 inches (39.420 mm) and an outside diameter of 3.165 inches (80.390 mm), matching the housing bore size of approximately 3.160 inches (80.260 mm). The seal thickness is 0.645 inches (16.383 mm), providing a secure fit around the pinion shaft. Constructed from polyacrylate, the seal offers resistance to heat and wear, suitable for demanding driveline environments. The Redicoat coating enhances corrosion protection, extending the service life of the seal in various operating conditions.

Compatible Vehicles and Applications

This differential pinion seal is compatible with a wide range of vehicles, including Chevrolet Blazer, C10 Suburban, Corvette, and Silverado models; Ford F-100, F-150, F-250, and F-350 trucks; Dodge Ram 1500 and Ram 2500; Jeep Cherokee, Grand Cherokee, Wrangler, and CJ series; as well as GMC, Honda, Isuzu, Lincoln, and other makes. It is designed to fit models such as the Bronco, Comanche, Grand Wagoneer, K10, K20, and more, ensuring proper sealing in the driveline and axle assemblies.

Common Issues Addressed by the National 5778 Seal

• Prevents oil leaks from the differential pinion shaft
• Reduces contamination ingress into the differential housing
• Maintains proper lubrication for driveline components
• Minimizes wear on the pinion shaft and bearings
• Helps avoid costly differential repairs due to seal failure

Installation Notes and Tips

When installing the National 5778 differential pinion seal, ensure the housing bore is clean and free of debris. Use appropriate tools to press the seal evenly into place without damaging the sealing lip or coating. Verify the shaft diameter matches the seal’s inside diameter of 1.552 inches (39.420 mm) for a proper fit. Lubricate the seal lip lightly with gear oil before installation to reduce initial wear. Follow vehicle-specific service manual instructions for torque specifications and assembly procedures.

Quality Assurance and Warranty

National’s 5778 differential pinion seal is manufactured to meet industry standards for durability and performance. The polyacrylate material and Redicoat treatment contribute to long-lasting service life under normal operating conditions. While specific warranty details may vary, National typically offers coverage against manufacturing defects to ensure customer confidence in the product’s reliability.