If you are tearing the whole axle apart and can clean out shavings from the inside, I'd say thread the hold and then put a bolt in it. This way, if you ever add an air locker or other actuated locker, you can just pull the bolt and not worry about having weird threads in the housing.
If you are NEVER going to use a locker, jusst stick a self tapper in there and you should be fine (I'd still thread it though, IMO.)
'97 Forest green. ~6" total lift, 8.8, etc. 36" TSL's, winch. You get the drill.