I have a 1979 Chev K10 with front wheel locking hubs.

The locknut and spindle thread (at the outer edge) has been partially
stripped. The thread that is not damaged is still usable. I cannot
remove the inner adjusting not because of the stripped portion. I have
tried to grind the stripped thread away (protecting the good thread by
undoing the adjusting nut up to the stripped thread) using carbide
grinding bits. All I have achieved is destroying the bits and polishing
the stripped thread.

I cannot use a steel file because the access is limited.

How can I remove the stripped thread? I believe the spindle is forged
steel. I have contemplated using a cold steel chisel, but do not want
to attempt until I have more info on possible solutions.
Hoping someone can help
Regards
Tony