Ford Repair: 1998 Explorer rear hub, rear hubs, rear hub

Question
How do you refill the rear hub with oil? It is the AWD model. I
found 1 bolt on top but when I removed it , it didn't seem like it
went down into the hub for a channel to pour the oil into>

Answer
A '98 Explorer doesn't have "sealed bearing" rear hubs.  It has a solid rear axle.  The rear axle is filled with gear oil.  There should be a fill hole near the front of the center (round) section.  The fill hole has a plug that can be removed with a large allen wrench.  The oil should be filled with the vehicle on a level surface until the oil is running out of the hole.  

The axle housing has several roller-type bearings inside and rubber, lip-type seals on the ends.  The axle seals and pinion seal hold the oil in while the axle's internal components turn in the oil.  

Hope this helps,

Dave