Those front cv shafts do turn in 2wd. It's sentral disconnect system so the front drivetrain does turn but the front driveshaft doesn't. Basically it just discoonects the front axle from the t-case.
I have a similar bump bump bump in the steering that is either the cv's, maybe the idler arm, or one Ford tech told me it could be the lower steering shaft. The steering shaft does have some play and the Ford tech checked the play against another truck, but the dummy checked abused lifted truck. Of corse the lifted truck is probably going to have loose parts due to all the strain.
When my front hub bearings went bad at 130K miles I had a bump in the steering also, but you could hear slight bearing (grinding) sound.
The cv's will sometimes "pop" when in a bind and when driving you can hear a thump thump sound. Other times they can be nosie free but still be bad and cause you to think a wheel is unbalanced or you have worn suspension parts.