I have 91 KingCab HB w/150,000 miles. Recently I have gotten this squeak, kinda sounds like fingernails across a chaulk board only when I have a constant speed, not during acceleration. I jumped on the bumper and had two people help me pull it side to side for suspension squeaks and do not think this is it. I also pulled the brake drums off, and replaced the shoes. After replacing the shoes, I still here the sound. Any ideas?? There is very little play in the last U-Joint before the transfer case, could this be the squeak? I'd appreciate any comments, and thank you if you do.