Yea, usually from my experience, the pinion bearing starts to go bad, and that will give you a whinning noise from the rear, and I have had rears do that for many many miles before it got bad enough that I had to replace it, as for the hub bearing, it is located right behind the wheel, it is the outer bearing assembly that is bolted to the spindle, unfortunatly it has to be replaced as a unit, you have to buy the whole hub assembly. I have seen them go for 90 to 200 dollars, I just bought mine from a guy on e bay for 96 bucks, and so far, so good, I can give you his seller ID if you want to check it out. Changing it is really not too bad of a job, but you have to try to narrow it down to which side is bad, that can get tricky, because that noise seems to vibrate right through the truck so it is sometimes hard to pin-point. A lot of people say to jack up the truck and get the front wheel off the ground and grab the wheel with both hands, one on the top and one on the bottom and try to move it to see if it has play, sometimes it works, if the bearing is bad enough it will move, but sometimes you can mistake it for a bad ball joint as well. I had bad ball joints on mine already, so I had to change them, so when I was changing them I decided to pull the CV joint out of the hub bearing and try to spin it, since I really didnt find any play coming from the bearing, and to my delight, when I spun the bearing it made crunching and grinding noises, so then I knew that it was shot, and I replaced it, and now my truck is nice and quiet, to be honest with you, the noise my truck was making was so loud I had to turn up the radio when I was on the highway because I couldnt hear it over the noise!! Anyway, I don't know what your mechanical abilities are so I am not going to go any furthur, if you need anymore help let me know and I will be glad to assist you. Just let me know.
Jack
