I don't think I would worry about castle nut or nylock, both will effectively do the same thing. Unless it's just a must have for you. Certainly is better than what your scamchanic did. As long as you have something that locks into place, and looks correct, I personally think you should be good.
My wife just brought up a good point, if your scamchanic also did the lift, please, for the love of God, have someone please check over everything he did. I don't trust him, and neither should you.
My wife just brought up a good point, if your scamchanic also did the lift, please, for the love of God, have someone please check over everything he did. I don't trust him, and neither should you.