Selector Shaft Seal Replacement

[clifford]

Having a problem removing this nut.



I can hold the cast piece OK but the whole shaft revolves within it when I turn the nut! Don't want to grip the shaft itself because of damaging it where it enters the seal.
It seems as if the shaft is unscrewing from the other end.

Any tips please?

[clifford]

Resorted to grinding through the nut with a Dremel. Cut as close to the thread as I dared and it came off easy as anything.