This shaft transmits rotary motion from the gearbox output to the feeder or auger drive within the header assembly. It connects the drive spigot on the header input to the driven component, synchronizing the rotation of the intake and conveying elements. A worn or bent shaft causes vibration at the coupling points and can lead to premature bearing failure in the driven unit. This replacement shaft is machined to the same spline and keyway dimensions as the original, so no shimming or adapter is required during installation. On reinstall, ensure the shaft is fully seated in both couplings and that the retaining hardware is torqued to specification.