Well hear is one way to check those. Crawl under the truck with the 4x4 NOT engaged. Try and turn the axle by hand. If you can't then the hubs are stuck in 4x4. Do you have auto hubs or manual hubs? Either way you should be able to turn the axle shaft.
I checked the drive shafts and the passenger side will not turn when set to auto. Now what?
Your hub is stuck in 4x4 even though it says auto. Pull off center cap then use a pair of pliers to release big clip ring.Pull out auto hub probably full of dirt and oxidation. Turn hub back and forth between lock and auto till it loosens up and it should work ok, reinstall.