National 240735 Manual Transmission Shift Shaft Seal

Manual Transmission Shift Shaft Seal for GM Applications

National 240735 is a manual transmission shift shaft seal built with nitrile sealing material for dependable oil control at the shift shaft. It is sized for a 0.750-inch shaft and a 0.999-inch housing bore, making it a direct-fit sealing solution for many Chevrolet, GMC, Pontiac, Buick, and Oldsmobile manual transmission applications.

Use this seal when servicing GM 3-speed and Saginaw/SM326-equipped vehicles such as the Chevrolet Corvette, Camaro, and G10, or GMC G1500 and C1500 models. Part number 240735 is also cross-referenced by Wix 46338 for the same application.

Key Features

• Nitrile sealing material for oil resistance in manual transmission service
• 0.750-inch inside diameter for the shift shaft
• 0.999-inch housing bore for proper seal fit
• 0.156-inch width for compact transmission sealing applications
• National Series 240000 oil seal design
• Direct replacement for many GM manual transmission shift shaft seal applications

Detailed Description

National 240735 is an oil seal designed for manual transmission shift shaft service where accurate dimensions and reliable sealing are critical. The nitrile construction helps maintain a tight seal against transmission fluid, while the 0.750-inch shaft size and 1.010-inch outside diameter support proper installation in the specified housing bore. This seal is used across a wide range of classic GM vehicles, including Chevrolet Corvette, Camaro, El Camino, Nova, and GMC van and truck platforms with Saginaw, SM326, or related 3-speed manual transmissions. If you are restoring or repairing a Chevrolet C10, GMC Jimmy, or Pontiac Firebird with the listed transmission setup, National 240735 provides the correct sealing profile for the shift shaft area.

Common Problems This Seal Can Address

• Transmission fluid seepage around the shift shaft
• Oil residue collecting on the transmission case
• Worn or hardened original seal material
• Leak concerns during manual transmission service
• Seal replacement needs on GM Saginaw and SM326 applications

Installation Notes and Tips

Confirm shaft diameter, housing bore, and transmission type before installation. Clean the bore and shaft surface thoroughly, and inspect for wear, scoring, or corrosion that could affect sealing performance. Match the application to the listed fitment, especially on Chevrolet Corvette, Camaro, G10, and GMC truck or van models with the specified manual transmission notes. National 240735 should be installed only where the dimensions and transmission configuration align with the vehicle listing.

Quality Assurance

National has supplied sealing solutions for more than 75 years and continues to develop products for modern and legacy vehicle service. Part number 240735 reflects that long-running focus on dimensional accuracy and transmission sealing performance for GM manual transmission applications.