National 415988 Automatic Transmission Extension Housing Seal

Overview of National 415988 Automatic Transmission Extension Housing Seal

The National 415988 automatic transmission extension housing seal is engineered for reliable sealing performance in heavy-duty vehicles. Designed specifically for Chevrolet, GMC, and Hummer models, this oil seal ensures proper transmission function by preventing fluid leaks and contamination.

• Inside diameter: 2.562 inches (65.070 mm)
• Outside diameter: 3.628 inches (92.150 mm)
• Thickness/width: 0.375 inches (9.530 mm)
• Material: Durable nitrile compound
• Redicoat coating for enhanced wear resistance
• Compatible with housing bore size 3.623 inches (92.020 mm)
• Part number: 415988, series 410000, type 41

Technical Details and Material Specifications

This automatic transmission extension housing seal is constructed from nitrile, a synthetic rubber known for its resistance to oil, heat, and wear. The seal features a Redicoat surface treatment that improves durability and extends service life under demanding operating conditions. With an inside diameter of 2.562 inches and an outside diameter of 3.628 inches, it fits precisely into the transmission extension housing bore measuring 3.623 inches. The 0.375-inch thickness provides a secure seal to prevent transmission fluid leakage.

Compatible Vehicles and Applications

The National 415988 seal is compatible with a range of Chevrolet, GMC, and Hummer heavy-duty trucks and SUVs. Specifically, it fits models including Chevrolet Silverado 2500 HD, Silverado 3500, Silverado 3500 Classic, GMC Sierra 2500 HD, Sierra 3500, Sierra 3500 Classic, and the Hummer H1. This seal is designed to maintain transmission integrity in these vehicles by sealing the extension housing effectively.

Common Issues Addressed by This Seal

• Prevents automatic transmission fluid leaks from the extension housing
• Reduces contamination ingress that can damage transmission components
• Minimizes wear on transmission shafts by maintaining proper lubrication
• Helps avoid costly transmission repairs due to seal failure
• Maintains optimal transmission performance and longevity

Installation Notes and Tips

Ensure the transmission extension housing bore is clean and free of debris before installation. Carefully align the seal to avoid damage to the sealing lip. Use appropriate tools to press the seal evenly into place without distortion. Verify the seal’s fit against the shaft diameter of 2.562 inches to ensure proper sealing. Follow vehicle manufacturer torque specifications and procedures during reassembly.

Quality Assurance and Warranty Information

National’s 415988 transmission extension housing seal is manufactured to meet OEM standards for fit and function. The nitrile material and Redicoat treatment provide reliable performance under typical operating conditions. This part is a zero duplication part, ensuring unique quality control and traceability. Warranty coverage details should be confirmed with the parts distributor or vehicle manufacturer.