crank shaft thread size

  5/8"  x 20 TPI ,  and most likely  cycle . ( I don't really know all this stuff, just know where to look).

The drive-side alternator crankpins are one-peice and beyond the main bearing shoulder have a reducing taper shoulder with a woodruff key( to take the engine sprocket), then a parallel section with a woodruff key (to take the alternator rotor) and then a 5/8  inch BS Cycle 20 tpi threaded section for the nut.  There are no screwed-in studs unless a Dynamo type crankpin has been modified as such.  Cheers, Howard

The Commando shaft has the same end thread but uses a sleeve nut. A number of belt drive conversions, for the heavy twins, use a similar set-up.