1969 Cooling Fan Nut Size Needed

[GrigioTR]

I have to replace my generator and am away from the house for awhile and have not had the chance to remove my toasted generator. I am hoping someone can tell me what the mm size is of the nut that holds the cooling fan on the generator shaft. If I have that information I can source the socket will hopefully have everything I need when I get home to do the replacement.

I have done a search on a number of sites and no place lists what size the nut is or socket needed to remove it.

As always, thanks in advance for your help.