2015 XLT supercrew, I installed an IWE delete kit (please lookup instead of asking here if you don't know what this is) quite a while ago after having countless IWE failures, it has been solid until recently and I'm getting a very loud popping/cracking noise coming from the driver's side wheel when in 4wd only under load when the wheel is turning.

Anyone know what this could be?

 

IWE or CV joint/axle would be my first guess. Check the CV boots for tears and grease flung out.

 

Your hub bearing or CV are the first things I'd look at. I can't see the eliminator causing a bearing problem, those go out on their own. Your CV is turning all the time now, and depending on if you have a leveling kit on, with the angle increase, could be the trouble causing a bad CV. I'll include a somewhat goofy video from a guy that removed his eliminators, and why. He talks about a "upper pinion" bearing, no idea what he's referring to there, don't think any pinion bearing is your problem anyway.

 

You may be driving in the wrong conditions while in 4x4.
If you don't know what the wrong conditions are, please look it up instead of asking.

Agreed with the posts above about possible culprits but it could be that you aren't driving your truck right. We shouldn't assume you do know, or do not know, how/when to use 4x4.

 

I had a leveling kit on the truck for maybe the first 20k miles, then went to a 6" rough country lift, which drops the diff to correct the cv angle, I think? I should also mention that I've got 120k miles on the truck so far.

 

Yes, you are right, an actual lift would keep the CV angles at a reasonable angle, but you say you now have 120K on the truck now. I've seen where trucks with much less mileage develop bearing, and/or CV problems.
I'm not all that familiar with that 6" lift. Is that an actual 4" lift with spacers added to get to 6"? Even then, a 2" spacer is not excessive.
Would you be able to provide a video? I'm still leaning towards a bearing or CV at any rate. With the removal of the IWE, that's the only things you have left, other than brakes.