Overhauling the shaft drive means renewing as many of the wear and damage prone components as possible. This will attain the best results, as interfacing used parts with new will lead to premature wear of the new parts, and a less smooth transmission of power from the gearbox through to the back wheel. The kind of power on, power off, "shunt" that a worn system delivers is unpleasant to say the least?
This component and perhaps some of those listed below maybe required when overhauling the front bevel gear: