Went to engage my 4-Hi a while back, successfully about 3-4 times due to my rear tires losing traction, during proper use (not dry pavement), then attempted again and got a grinding/howling noise from under my feet. I immediately shifted out of 4-Hi into neutral and the noise continued until I came to a complete stop. I shifted into 2-Hi and the noise was gone. Another test later had the same symptoms.
So far I’ve found it could be (not sure if these are right), U-Joints, some electrical motors responsible for shifting on the transfer case (not applicable to my manual shift case) some motor for locking the front diff (not sure if this is applicable-nothing mentioning it in repair manual), complete and utter failure of the transfer case and/or front diff.
Any help pinpointing the issue is appreciated.