My dad has a 94 K1500. He told me over the weekend that when in 2wd, it sounds like the front differential is trying to engage. If he puts it in 4wd everything works fine and quiet. I have not checked myself yet, but I thought I would throw it out here to you guys to see if someone else has had this problem and could tell me what to expect. Sorry it's so vague, I'll fill in more information after I look at it.