National 304-DD Manual Transmission Countershaft Bearing - Center or Rear

Overview of National 304-DD Manual Transmission Countershaft Bearing

The National 304-DD is a precision-engineered manual transmission countershaft bearing designed for reliable performance in select Ford, Mercury, Nissan, and Toyota vehicles. This single row radial ball bearing supports smooth countershaft rotation, essential for maintaining transmission efficiency and longevity.

• Single row radial design for consistent load handling
• 0.787 inch (20 mm) bore diameter for precise fitment
• Outer diameter of 2.047 inches (52 mm) ensuring compatibility with specified transmissions
• Width of 0.591 inches (15 mm) for optimal space utilization
• Inner and outer race radii of 0.040 inches (1.02 mm) for durability and reduced wear

Technical Specifications and Design Details

The National 304-DD bearing features a 20 mm inner race bore and a 52 mm outer diameter, making it suitable for manual transmission countershafts in various vehicle models. Its single row radial ball bearing design supports radial loads effectively, contributing to smooth gear engagement and reduced friction. The bearing’s inner race width and outer race width both measure 15 mm, providing balanced support within the transmission assembly. The A-7 type and 300 series classification indicate its standardized dimensions and performance characteristics, aligning with OEM requirements.

Compatible Vehicles and Applications

This manual transmission countershaft bearing is compatible with a range of Ford, Mercury, Nissan, and Toyota models, including but not limited to:

• Ford F-100, F-250, F-350, E-250 Econoline, E-350 Econoline, and Econoline Club Wagon variants
• Mercury Colony Park and Marauder
• Nissan Pickup
• Toyota Land Cruiser and LTD

Using the National 304-DD bearing ensures proper fitment and reliable operation within these specific manual transmission systems.

Common Issues Addressed by the 304-DD Bearing

• Excessive transmission noise due to worn or damaged countershaft bearings
• Vibration or rough gear shifting caused by bearing failure
• Premature wear of transmission components from inadequate bearing support
• Overheating in the transmission assembly linked to bearing friction
• Reduced transmission efficiency and potential gear slippage

Installation Notes and Tips

• Ensure the transmission is clean and free of debris before installation
• Use proper tools to press the bearing onto the countershaft without damaging the races
• Verify the bearing orientation matches OEM specifications
• Check for smooth rotation after installation to confirm correct fitment
• Consult vehicle-specific service manuals for torque and assembly procedures

Quality Assurance and Warranty Information

National bearings are manufactured to meet industry standards for durability and performance. The 304-DD manual transmission countershaft bearing undergoes rigorous quality control to ensure dimensional accuracy and material integrity. While specific warranty terms may vary, National typically offers coverage against manufacturing defects, providing confidence in the product’s reliability for compatible Ford, Mercury, Nissan, and Toyota transmissions.