So about 2 weeks ago my 5.3 started making a loud revolving squealing/screeching noise that relates to RPMs. I immediately thought belt, but it was definitely more of a bearing noise and is certainly something in the front dress. I removed the belt and moved all of the pullies by hand (except for the crank of course) and the only one that made noise was the tensioner pulley. After replacing the tensioner pulley the problem went away for a few miles and came right back. My issue is that because of the way the noise reverberates under the hood I cannot pinpoint what accessory it is. The only accessory that has any kind of significant resistance is the alternator, but the frequency of the squeal is too slow to be that tiny alternator pulley. This is such a novice problem and am embarrassed to post it, but I cannot seem to track it down. Any advice for troubleshooting?