I will check the front UJ's as as you say sound travels and can easily be misread. That said I had a good listen and look today and the noise definately seems to be coming from the rear axle and I would go further and say from the wheel end. Its a 2.5 diesel and I checked the box levels a couple of weeks ago with the vehicle on the level. Could the hub/halfshaft end float, if excessive due to some other issue, cause the brake shoes/hub/drum to contact when they shouldn't when turning sharp? The outer half shaft bearings have no apparent play, don't make funny noises and spin freely.