My transfer case will not grind in 4Hi. But in every other 'gear' it will grind like crazy. Well, usually. After I shift back into 4Hi aftre i finish wheelin it'll grind for a while, and be ok, and then grind over bumps. I'll mess with it a little until it stops grinding. And this grinding is LOUD. People will look at me on the road and try to figure out what's wrong. I have pulled up to my friends' house and he says he heard me from over a quarter mile away. I canot figure out what it is, and it scares the hell outta me. I have an NP203 from a 78 K5 mated to a TH350.