Are you sure they are Auto hubs and not FULL TIME ?
Auto hubs will say AUTO on the caps most times, and Full time hubs will just have a chrome cap pushed over the end.
Is the Jeep Quadra Trac ? if so, then it is full time and you'll need more than just manual hubs to make it part time. ( if rear diff is offset and the frnt and rear drive shafts are inline to the pas side of vehicle, more than likely you are Quadra trac )
Kevin