I don't know of Yamaha having any kind of a diagram that would give that info.
The shaft size is about 1.064 or 1-1/16 inch. You will have to do the math if you need a metric number.
Thanks PZ1. I wonder if 7 tooth anti ratchet drivers will work? Wahl bros does make them....but I have regular 7 tooth drivers in it now and it appears the anti ones would hit the rails. Kind of an expensive lesson. Anyone tried it?