if it has manual hubs they are on the front wheel, it should be a
little cone shaped object coming out of the center of the wheel, you
can turn the hubs there, thats if they are manual, with a sahara i
think that they are, but if not then its automatic locking hubs, then
all you have to do is pull the shifter back to 4low or 4high and it
will be engaged, if its all working right that is