I have a very high-pitched squeal that comes from somewhere near the rear axle of my truck. I have a 14-bolt semi-floating rear axle with 208k miles on it. Symptoms: -the noise sounds almost like needle dragging on peice of glass/smooth metal...it is that high. -Noise is constant, not undulating -the noise is not very loud, if I had a radio it would drown out noise even at low volume -Noise stops below 5 mph -Noise DOES NOT change at all (volume/pitch etc) when I step on the brakes. -I jacked up the rear end of the truck and put it in gear, sitting back by the axle I could hear the noise, but it is so high pitched that I could not isolate where it is coming from? -rear end does have fluid, I double checked. I just want to be sure this isn't something that I should repair now to avoid major/expensive repair later? LIke an axle bearing or pinion bearing in the differential that is going to heat up and melt something together!