If this is of any assistance to anyone because I have seen this question many times on the forum - I had a steadily increasing droning noise coming from the back end that was road speed and not engine speed relative. It started around 40 mph getting ever louder as the speed increased and eventually, over the last couple of weeks, a slight whirring noise could be heard as well. I have had several cars where the wheel bearings went and did all the usual tests on the Forester - left and right bends, braking/ accelerating etc, but none of these tests indicated wheel bearings so I suspected the diff was gone seeing as the tranny seized and was replaced last year. I got the diff replaced and b...ger me, it was still there. Yesterday I had both rear wheel bearings replaced and bingo, proplem solved. Foresters are known for wheel bearing issues and if you have these noises coming from the back of your Foz, wheel bearings might be the more econimical route first as I was quoted 800 euro to rebuild my diff (plus fitting /removal) but went for a salvage unit in the end that cost me 350 euro all in. I would have been exceedingly pi..sed off if I had gone for the rebuild. I got bearings from Import Car Parts - Japanese car parts for Subaru, Nissan, Honda, Toyota, Lexus, Mitsubishi and more for just over 100 euro a pair plus 150 for the fitting - hindsight is a wonderful thing. Hope this is of help to some of you.