My 91 K1500 started grinding and jerking when I hit something submerged in the snow a few years back. I thought it was damaged and I just haven't had the money to get it fixed so i never took it in. But what MrShorty says makes me have some hope. I'm going to get in my Chevy and put it in 4wheel right now. I never thought about the fact that my spare tire was smaller than my other 3 and that could be causing those problems. And yes, i had a spare tire on it for a couple years. I've not tried it since I got the correct sized tire on. I'll have to let you know how things go. Thanks MrShorty!