There is no such thing as a "good" LSD that is 16 years old. I can promise you there is no "limited" left in that diff. Unless it happens to have a gear ratio you are looking for, it is probably not worth the time/money to mess with.

As far as rebuilding, I am unaware of any available parts, short of a new carrier/LSD from Isuzu. You could call Merlin at St Charles and see what he can scare up, but in all my years on these boards, I cannot recall anyone who rebuilt a LSD.

It would be money better spent to look at the lunchbox locker Matt at Independent4x has or an ARB. It really depends upon what you are looking for. If you are going to be wheeling it, then take a serious look at a locker of some sort.

Good Luck,
Michael