Paul - I agree with Mark/Dyn Blin. But u-joints are going to be running ~3 times faster than the wheels, so they'll sound different.
On u-joints you can sometimes tell by sliding under the truck and trying to move the driveshaft sideways. Or turn it and see if there is play in the joint.
Wheel bearings can be checked by jacking that corner up and pulling out on the bottom of the wheel while pushing in on the top. And vice versa. You are looking for movement of the hub, and there shouldn't be any.
Having said that, bad ball joints can give movement of the hub, but it usually takes more force to do that.
Gary, AKA "Gary fellow":
Profile
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI