The Eaton Fuller Mainshaft, part number 239409, is a genuine Eaton Fuller transmission component designed for heavy-duty truck applications. The mainshaft is a core internal drivetrain part, transferring torque through the transmission gear stack. Eaton Fuller transmissions are a standard across commercial trucking, and using a genuine Eaton Fuller mainshaft helps ensure proper gear engagement and dimensional accuracy within the gearbox. Contact Pro Gear and Transmission to verify this mainshaft fits your specific transmission model before ordering.FeaturesGenuine Eaton Fuller mainshaftPart number: 239409Designed for heavy-duty commercial truck transmissionsCore internal component for torque transfer through the gear stackCall us to confirm fitment for your specific Eaton Fuller transmission