Remove the nut if you can.
Go to tool supply shop and show them the nut. You need to purchase a thread chaser and a tap of the correct size to repair the threads of both the shaft and nut. Just get jobber tools to save bucks.
Once assembled use green Lock-Tite.

Understand that purchasing and installing a new rod end will be cheaper and easier unless you like to own tools. I have that sickness.

If the nut will not spin off you must cut the taper shaft off right below the nut. Use a hack saw or cutting wheel on a grinder. Unless you have a nut splitter in which case this is your easiest bet: cut the nut and replace the rod end.

__________________
I don't know the same things that you don't know.

Shayne

85 W126 SD OM617.951
87 409D 650S OM617.913
93 E34 Touring M50B25TU
02 E46 Sport M54B30TU