Try a search for hubs at Ack's FAQ (the link is in my signature).
There you will find two rebuild links for the Asin hubs.
Hopefuly, they will help you with any problems having to do with the hubs themselves.
The only thing that I can think of besides the hubs going bad is separation inside one of the halfshaft boots or possibly inside the differential housing -- assuming that you have been wheeling your truck hard recently. Those kinds of failures don't happen to trucks that don't go offroad, though.