2004 F150 FX4 5.4

My 21 month old kid loves pushing buttons and turning ***** on my truck. I left the house the other day and drove 50 miles to work with no noise or any indication of problems. Left work and noticed a grinding/rubbing noise, but only when turning right. Thought it was something rubbing until I got back into town. When slowing down I felt like I was in 4WD and when I took sharp town turns there was terrible clunking (like 4WD engaging roughly). I got out and looked around. When I got back in I saw that my kid had put me in 4WD Low. It never fully engaged, so I didn't feel it, and the light never came on. I've tried putting it in and out of 4WD tons of times and a grinding/whirring persists. The noise actually goes away when I engage 4WD High when I'm going straight. When I turn it still goes in and out.

I have replaced a vacuum actuator, wheel hub assembly and the CV before on similar year fords. I'm just wondering what I most likely damaged, so I can get all the parts I need before pulling it apart.

My 4WD worked fine before this, so I'm pretty sure it has nothing to do with vacuum or anything like that. Although it does sound like I have a vacuum leak and the 4WD is trying to engage all the time.

Any ideas would be great. Otherwise I'll just get CV, actuator, and new hub and work my way in.