Sportrak Clunking Noise


Have got '94 Sportrak, and recently have experienced clunking noises coming from the front passenger side wheel. This clunking noise happens when reversing in both 2WD and 4WD. It is continuous in reverse, then only happens for a few seconds once pulling away, then stops. It only happens straight after using reverse.
A friend has suggested it might be the automatic hub - any ideas?
Help would be greatly appreciated, as can't find any specialists in local area.
Many Thanks. Mr T