2008, CRD, QDII. 81K.
Let me clarify the "clunk" word. It is "clunking" when rubber parts that should prevent metal parts from contacting each over are getting worn and one metal part starts beating the other one (on the road humps etc). Am I right? If yes, the sound that I can feel (not only hear) definitely is not the clunk.
It rather reminds me a great supporting bearing (like in McPherson suspension) that is full of sand, attached to the huge spring and what I am, nevertheless, trying to turn.
I have changed the axle fluid less than a year ago (< 10K), the transfer case's fluid was changed a week ago, the gearbox' fluid was changed a couple of months ago.
P.S. The front pads are pretty worn.
The QDII has LSD's and if the axle fluid wears out or they didn't use the correct or correct amount of friction modifier to allow the clutch plates to slip well enough, you get noise and binding in low speed turns. Check your O.M., I think the severe schedule (maybe the normal for QDII) is every 15k miles. If the correct additive wasn't used that might be the problem or maybe the fluid was contaminated?
When you turn at low speeds, there is a lot of torque in the driveshafts and wheels moving at very different speeds, differentials turning, etc, compared to just backing up straight; so if there is any lash/free play in the driveshafts or the mounts for differentials,
A clunk, is a clunk, it's a noise of something impacting something else, doesn't have to be metal on metal, it just has to be hard enough to make a loud impact noise. Worn out mounts are often metal on rubber, there is just enough movement with momentum behind it, it sounds like a hammer banging on the floor.
What you're describing sounds like the steering bearing plate in the macpherson strut, and that would make a grind noise, NOT a clunk, unless you're talking bearings so worn out they seize and clunk. Do you have a grinding noise?
I thought of one else, the Sway Bar bushings, it could clunk turning as you back out of the driveway, but it would also clunk when driving normally, something you haven't said is a symptom.
The sway bar twists as the body leans, thus making a spring force to resist the twist. That will push up and down on the bushings that mount it, and up/down pressure reverses as you turn the opposite direction. The sway bar bushings can wear, the hole the bar goes through elongates and lets the bar move up and down some. So when you reverse forces on the bar, it quickly is bounced from one end of the elongated hole to the other and makes a clunk when it hits the opposite side.