The noise is coming from the front. General proximity would be anywhere along the front axle area.

How can I tell if the front U-joints are going bad?

I'd try to replicate the conditions and have someone drive it while you walk next to it and identify the source. All i can share is my experience, and when my axle u joint went, I could feel the binding in the wheel a week before it made any noise. I thought it might be tire cupping and i needed to rotate the tires, then it started squeaking. Same as you described, like a shitty door hinge. I knew what it was right away. I know that the u joints click when they completely fail, i've heard them. But i have also felt them bind and and squeak when the cap seals start to go and you get that squeak under load.

I don't remember if you said the squeaking was rotational, like squeaking related to tire rotation or if it was completely random and related to suspension articulation.

Like others have said, CV joints are going to grind or click when they fail not bind. With the binding and squeaking you describe, my money is on the front DS u joint. Since u joint aren't CV, there is addition cyclical force placed on the caps under angle and load. If it is that, you have a long time until it fails completely and its a $70 fix ($30 for the new joint and $40 to have a local shop press it in)... again assuming that is what it is.

Thing that really sux is that a lot of this is just trial and error. Got a buddy with a factory shaft? The easiest thing would be swap shafts real quick and see if problem persists. At least it would narrow down or eliminate the front DS quickly.

Nope, I was actually thinking of picking up a factory DS off of Craigslist to try that out, then I kind of started thinking about not wasting my time and money and spend some more on an Adams DS but I hate the thought of just throwing parts at a problem. I have a trip coming up to Silver Lake sand dunes, and wanted to fix this problem before then. Wanted to try to avoid a situation of something breaking while offroading on the trip, although the benefit would be of me knowing exactly what's creaking and needs to be fixed. ;)

That sounds like a very likely diagnosis. I would say it is somewhat rotational. I turn the steering wheel, move forward to approach a climb up a small hill and right when the tires first start going up the incline of the hill is when I hear the creak sound, then it stops as I'm climbing up the incline, and then creaks again, as I go over the crest of the hill and when I 1st begin to climb back down, it will creak. Definitely a wooden door creak type of sound.

I'll see if I can find a way to mount a camera underneath and take some video and aim the camera towards the U-joints.

Sounds more like a bushing that's creaking to me. Maybe a control arm binding a little. It wont necessarily make the same noise by just jumping on the bumper.
Maybe even the sway bar mounts

Just a thought

Thanks for the suggestions. I still need to put a camera underneath it and take some video. However, if it was a bushing or control arm, then why would the sound go away when in 2WD?

My bad. I was focused on the "flexing" part and missed where you took it out of 4WD. I haven't heard a driveshaft creak. All the JK driveshafts I have heard start clicking when they start to go.
Just going over things in my head.

The only other thing I could think to throw into the factor is the added torque to the front drive line while in 4WD. I'm kinda stumped on this one. I just cant think of anything else that would make a creaking noise. But then again, what I imagine as a creaking noise could be completely different then the creaking sound you actually have. LOL

Hope you figure it out. I'm curious now.

I would eliminate anything you think is obvious, then start thinking "outside the box" on possible causes. Sometimes its the things you would least expect. Good luck!

Is your front axle the standard D30 with BLD? Or do you have the limited slip?

I was just thinking if its the BLD, maybe the brake is being applied (correctly or incorrectly)to one side do to the BLD system?

Now I'm just throwing things out there:rotflmao2: But that was another thing that could "creak" so I had to...

It is the open Dana 30. So I can't elliminate that possibility. I'm going to the sand dunes next weekend. I was hoping to get this figured out before then, but I've been working on so many other things, I haven't had a chance to dig into this enough. Changing trans fluid this weekend.

Just hoping something doesn't break on the dunes. I'll have tools so pulling a front DS shouldn't be too difficult if it's the U joints.n