I have just finished restoring a 1940 South Bend 9C lathe. I am now trying to get my head around the change gear configurations. The stud and screw gears have a 9/16” bore with a keyway, but the banjo mounted idler gears have a 5/8” bore used with a bushing to reduce the bore to 7/16”. Does this mean you can’t use a screw/stud gear in a position on the banjo? From the chart it appears to only be a problem for the 80 tooth gear which is shown both in screw and idler locations. Does this mean two different 80 T gears with different bores are needed? Has. Anyone made a bushing with a 9/16 OD and a 7/16 ID to mount the 80 T screw gear on the banjo?