Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
There has been a service bulletin for that type of concern. Here is what it states.
Bulletin No.: 03-03-08-002B
Date: November 30, 2005
This bulletin is being revised to update the correction and parts information. Please discard Corporate Bulletin Number 03-03-08-002A (Section 03 - Suspension).
Some customers may comment on a rattle or squeak type noise coming from the front of the vehicle.
The front shock absorber plastic pilot ring may be wearing out, causing the shock to misalign in the insulator.
DO NOT replace the shock. Replace the lower portion, P/N 15834275 , of the upper insulator assembly using the procedure listed below. This new insulator has a taller plastic pilot ring that is attached to the metal sleeve to aid in the proper alignment of the insulators.
Right, you did say a clicking. If the U-joint is so bad that it is squeaking in 4WD, then it might be what you are hearing in 2WD when the shaft has no load on it. You will want to be sure though that it's not a brake pad or something simple like that.
If it seems to be on the left side, (more than the right) it could also be the CV joint on the axle.
Well, that would be considered a first order vibration, (sound) one time with each revolutoin. That would narrow it down to either the hub, bearing, axle and of course, differential.
If it were more of a 2X per revolution then it would be a second order and so on. Sometimes you can have a couple of different things that will give you more than the typical first, second and third order vibrations, (like something loose and sounding very random)
It of course helps to have an electronic "chassis ear" litening device, (most of us don't) or to duplicate the noise on a lift with a stethescope to find the exact location of it.