FAG SS3644 Manual Transmission Seal - Front or Inner

Manual Transmission Seal for Ford, Lincoln, and Mercury

FAG SS3644 is a manual transmission seal built for applications that use a .750" shaft and require a precise sealing fit. It is engineered with a metal spring seal design and nitrile sealing material to help keep transmission fluid where it belongs while blocking dirt, dust, and moisture.

Compatible With a wide range of Ford, Lincoln, Mercury, Mazda, Jaguar, and Jeep manual transmission applications, including many Ford F-150, Ford Ranger, and Ford Mustang models. The FAG SS3644 is also referenced by National 7929S and NGK 7556 for the same application.

Key Features

• Part number: SS3644
• Manual transmission seal with metal and spring construction
• Nitrile sealing material for dependable fluid sealing
• Bore diameter: 1.062 in. / 26.975 mm
• Seal outside diameter: 1.066 in. / 27.076 mm
• Seal width: 0.75 in. / 19.05 mm
• Designed for .750" shaft applications
• Built to help protect transmission components from contamination

Product Details

FAG SS3644 is specified for manual transmission sealing applications where dimensional accuracy matters. The seal’s nitrile material and spring-loaded metal design are selected to maintain sealing contact and help reduce leakage over time. This part is used across many long-running Ford truck, van, and passenger car platforms, including Fits 1975-2009 Ford F-150, Fits 1983-2008 Ford Ranger, and Fits 1996-2004 Ford Mustang, along with numerous Lincoln, Mercury, Mazda, Jaguar, and Jeep applications listed in the fitment data. For buyers searching by vehicle, this seal is a direct match for many Ford F-250, Ford E-350 Super Duty, and Lincoln Town Car manual transmission applications with the .750" shaft specification.

What It Helps Address

• Transmission fluid seepage at the seal interface
• Contamination from dirt, dust, and moisture
• Grease or lubricant loss around the bearing area
• Wear caused by an aging or hardened seal
• Service issues tied to incorrect seal dimensions

Installation Notes and Tips

Verify shaft diameter, bore diameter, seal outside diameter, and seal width before installation. Confirm the transmission position and application notes in the fitment list, especially for vehicles marked Inner or those with manual transmission seal notes. Clean the sealing surface thoroughly and inspect the shaft for scoring or wear before installing the new seal. Proper alignment during installation helps prevent premature leakage.

Quality Assurance

FAG designs seals to meet vehicle manufacturer specifications and works with suppliers to maintain FAG quality standards. The SS3644 is built for demanding wheel-end and transmission sealing requirements where contamination control and fluid retention are critical.