Timken 415988 Automatic Transmission Output Shaft Seal

Timken 415988 Output Shaft Seal

The Timken 415988 automatic transmission output shaft seal is built for direct-fit service on select Chevrolet Silverado HD, GMC Sierra HD, and Hummer H1 applications. It helps retain transmission fluid at the output shaft while keeping dirt and debris out of the sealing area.

Compatible With 2001-2018 Chevrolet Silverado 2500 HD, 2007-2018 Chevrolet Silverado 3500 HD, 2002-2018 GMC Sierra 2500 HD, 2007-2018 GMC Sierra 3500 HD, and related HD truck applications.

• Precision sealing design for fluid retention and contamination control
• Reinforced outer case for added durability during installation
• Ribbed rubber inner diameter helps seal minor shaft imperfections
• Internal contamination exclusion system helps block debris entry
• Vent holes promote lubricant flow around the seal lip to reduce heat buildup

Detailed Product Overview

Timken 415988 is an automatic transmission output shaft seal engineered for vehicles that rely on a stable seal at the transmission output. It is a practical replacement for worn or leaking seals on Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500 HD, GMC Sierra 2500 HD, GMC Sierra 3500 HD, and Hummer H1 models listed in the fitment data. This part cross-references National 415988 and SKF 25661 for the same application.

The seal’s reinforced outer case helps resist damage during installation, while the ribbed inner diameter supports a tighter seal on shafts with minor wear. Venting features help move lubricant around the lip area, reducing heat concentration at the seal surface.

What This Seal Helps Address

• Transmission fluid leakage at the output shaft
• Contamination entering the seal area
• Seal wear from heat buildup
• Reduced sealing performance on shafts with minor imperfections
• Damage caused by a weakened or distorted outer case

Installation Notes and Tips

Inspect the output shaft surface before installation and clean the sealing bore thoroughly. Replace the seal if the shaft shows scoring, corrosion, or excessive wear, since surface damage can affect sealing performance. Verify the application by year, make, and model before installation on 2001-2018 Chevrolet Silverado HD and 2002-2018 GMC Sierra HD trucks.

Quality Assurance

Timken oil and grease seals are designed with precision sealing features and contamination control details to support reliable service in drivetrain applications. Use this part number, 415988, when matching the correct automatic transmission output shaft seal for the listed vehicles.