Driveline Howling Fixed! 2000 V70XC AWD

[methos]

10 months ago we started noticing a howling noise that increased and decreased with speed. It got steadily louder as time went on. I tried several diagnostic solutions with no success. The local garage changed the bevel gear & differential oils, replaceing both rear wheel bearings left rear of which really needed it with no change to the howling. I finally took it to a shop that had "chassy ears" equipment and they diagnosed the torque tube input bearing. During my research I had been reassured that that complex system (inside the aluminum housing right in front of the rear differential) never goes bad so I was leaning toward a refirbushed Colorado Driveline driveshaft; those guys seem to provide a great product. I had also been quoted $2,500+ to replace the whole torque tube system. My new garage spent 3 hours ($300) and bearing ($60.95) freight ($52) to fix the howling for which I am very happy. The bearing was "press out, press in" so I couldn't have done it myself.
Note re: Left rear wheel bearing; I had ABS issues and ended up replacing both rear sensors and I now wonder if the worn wheel bearing may have had something to do with it.
I ended up replacing a bunch of parts and fixing some other problems we came upon along the way. It was rather expensive but at 154,000+ I feel pretty good about it and we're ready to put some more miles on the car. We really like it. I would also like to add a comment about removing the driveline completely to make a fwd car out of it. I bought the XC for the AWD. Nuf said.