'93 front hub replacement

Could someone tell me what size the front hub nut is for '93 MGM?
Chilton's manual recommends that the front hub nut and the dust cap be replaced. Is it absolutely neccessary to replace them?

It is not absolutely recommended, but it is a locking nut and once removed the locking portion is no longer useful. So it is highly recommended to replace nut once removed to keep it from loosening and possibly cause a wheel to come off. Cant remember right off what size nut is though.

Thanks, way2old.
I'll be replacing the nut. Once I get a new nut, I should be able to prepare the right size socket.