If you have a vintage Mooney you know about AD 77-17-04 which requires removing the control wheels every 500 hours and inspecting the shafts for cracks with dye penetrant. All M20 control shafts are the same outside diameter. People talk about the newer planes having a thicker shaft, the difference is in the thickness of the wall of the shafts, with the older M20's at 0.04 and the newer M20's at 0.06. The difference in the thickness of the shafts obviously results in a smaller inside diameter. T