This shaft transmits torque from the grain unloading drive to the auger assembly. It is a splined component that engages with matching internal splines on the driven hub, converting rotational motion from the drive source into auger rotation. Wear on the spline teeth or shaft surface causes backlash, resulting in intermittent drive engagement and reduced unloading efficiency. This component is manufactured to the original spline profile and shaft diameter, ensuring correct engagement depth and load distribution without requiring shimming or adapter sleeves.