Eaton 23566 Transmission Input Shaft For Fuller Transmissions

The Eaton 23566 Transmission Input Shaft is a replacement component for Eaton Fuller Road Ranger transmissions, designed to transfer engine torque into the main gear train in heavy-duty trucks that rely on Fuller gear sets. This shaft features a 10-spline interface and 18 teeth, providing the engagement geometry required by compatible Road Ranger gear trains. Identified by the part numbers 23566 and 20535, it is built to fit the Eaton Fuller transmission family used in commercial linehaul and heavy-duty applications. In operation, the input shaft sits at the front of the transmission and interfaces with the clutch assembly to transmit power to the gearset, influencing shift feel and overall drivetrain reliability. This part is specific to Fuller Road Ranger applications, so users should confirm the spline count and tooth count match their transmission model before installation to ensure proper alignment and performance. By using the correct input shaft, fleets and repair shops can maintain consistent shift quality and prevent premature wear in the transmission’s front-end assembly.