Front end moan.
 

I have experienced this issue 2 times and it only seems to do it after wheeling after 2+ hours. Typical trail consists of many washouts, steep inclines and declines. After about 2 hours of trailing, when turning left or right I start to hear a moaning sound. Only happens when I am turning left or right while riding the trail. I am in 4-low almost the entire time due to the extremely steep inclines, averaging about 5MPH or slower. 2.5" lift, 32" tires, stock steering setup, jku sport, 3.21 ratio. I have changed front diff fluid, no metal pieces etc, same issue. When I first get on the trail it makes no moaning sounds. Just after heavy wheeling for the 2+ hours.

You may be in need of a cooler for your power steering. I haven't had the issue but if you're steadily working the steering and that's when it starts moaning then that may be a good place to investigate.

2012 JKU- how many miles and when was the power steering fluid last serviced?

If it sounds anything like this............
https://drive.google.com/open?id=1lG...lqQu9NpE0g41C7

and your front axle U-Joints look like this......
https://doc-14-6k-docs.googleusercon...zvP7RGJlsfRvPv

Then I can tell you from experience, that your front axle U-Joints need to be replaced. Your description sounds similar to my experience.

See here:
https://www.jk-forum.com/forums/modi...r-lift-343000/

The manual says that color and odor -should not- be used as an indicator of fluid life. I would say at 100k miles, where you are, to get as much out and replace the fluid with fresh fluid. I used a turkey baster. Lift the tires off the ground, rotate lock to lock, replace some fluid, rotate lock to lock, replace some fluid, and just keep going until the fluid looks mostly clean. The 07-11 called for Mopar ATF+4 but check your manual.

Find the moan, and shotgun to the head seems to work best.

You're likely on the right track with the power steering then. :D