National 481181N Manual Transmission Input Shaft Seal

National 481181N Manual Transmission Input Shaft Seal

National 481181N is a manual transmission input shaft seal built for precise sealing performance in older GM drivetrain applications. With a polyacrylate sealing material and Redicoat treatment, it is engineered to help maintain fluid control at the transmission input shaft where wear and leakage often begin.

Key Features

• Manual transmission input shaft seal for transmission sealing service
• Polyacrylate material for durable sealing performance
• Redicoat surface treatment for improved installation and sealing contact
• Inside diameter: 1.625 in. / 41.280 mm
• Outside diameter: 2.129 in. / 54.080 mm
• Thickness/width: 0.250 in. / 6.350 mm
• Housing bore: 2.125 in. / 53.980 mm
• National 481181N, Series 480000, Type 48 oil seal

Detailed Description

National 481181N is an oil seal designed for the transmission input shaft area, where consistent sealing is critical to keeping lubricant contained and contamination out. National has supplied sealing solutions for more than 75 years, and this seal reflects that focus with a dimensionally specific design: 1.625-inch shaft diameter, 2.129-inch outside diameter, and 0.250-inch width. It is a direct-fit style seal for service work on GM manual transmission applications, including Chevrolet Blazer, Chevrolet C10, GMC Jimmy, and GMC C/K truck platforms listed in the fitment data. This part cross-references NGK 49633 for the same application.

What This Seal Helps Address

• Transmission fluid seepage at the input shaft
• Oil residue around the bellhousing area
• Seal wear from age, heat, and mileage
• Contamination entering the transmission through a worn seal area
• Service needs on GM manual transmission input shaft sealing points

Installation Notes and Tips

Verify shaft diameter, housing bore, and seal width before installation to confirm the correct match. Clean the bore and shaft surface thoroughly, and inspect for scoring or corrosion that could affect sealing. Use care during installation to keep the seal square in the bore and avoid damaging the sealing lip. For fitment verification, this part is listed for applications such as Fits 1975-1977 Chevrolet C10, Fits 1978-1986 Chevrolet K10, and Fits 1968-1974 GMC G15/G1500 Van, along with additional Chevrolet and GMC manual transmission applications shown in the fitment data.

Quality Assurance

National is a long-established sealing brand known for premium sealing solutions and ongoing product development for modern and legacy vehicles. The 481181N is built to the listed dimensional specifications and material requirements for service use in compatible GM transmission applications.