check for things wrapped around the axle/tire that could be whacking the truck from underneath. If there's nothing flapping, then we'll need some more info, like how fast the clicking noise is, does it increase with speed, is it louder outside of the vehicle, does it make the noise even when the truck isn't moving, and do you have the AWD (all wheel drive) version or the rear wheel drive version?
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
I've abandoned this ship in favor of other forums that actually have active admins.