I'm rebuilding a 9N right now.  I have a problem with determining the part number for the chrome sleeve that goes over the end of the pinion gear/shaft assembly which is inserted into the pinion bearing.  Yesterday's Tractors (a part supplier) would like to sell me the part, but they don't know which one I need.  They have three listed.  In lieu of buying all three, does anyone have any suggestions on how I can select the correct one?