Unfortunately, someone more experienced than I is going to have to help you here. All I can say is that to me it sounds like the center differential is jammed locked. Why it would get stuck, I don't know, but I have never had any grinding at all, ever. Also, that's not good. If you really are running around with the center locked up, you'll be burning more fuel than necessary and I think the book says it is bad to be running more than 40 in this way (yes, I know 4H unlocked can be shifted in and out of up to 62mph). Basically what I am saying is BUMP, someone step in here and help! <img src="/forums/images/graemlins/scared.gif" alt="" />