chirping in drivetrain..

[lakailimited06]

i've got a chirping sound coming from under the truck..it comes and goes but it increases and decreases depending on my speed im sure its most likely u joints going..

what spins on these things in 2wd with the hubs unlocked? i've never dealt with manual hubs before..does just the rear driveshaft spin?

what about the front axle shafts if they spin in 2wd it could be the u joints on them as well...