Clunking when braking isn't always a diff problem, although it sounds as if you deffinitely had some issues. Check your driveline, a bad U joint or a worn out slip yoke will do that. In my first Cruiser, an FJ40, I had trashed spider gears and the shaft they ride on. It would bind up when I put it in reverse and then clunk and start to move. There was excessive axle movement from side to side, which in my ignornace, I thought was axle bearings. The axle bearings are really tough, and unless there is vertical play, they are probably fine. The bearings will likely wear out the axle shaft itself before they wear out, at least that has been my experience. If the axle moves in and out more than say, 1/16", then you migt have issues with spider gears, side gear bushings or the spider shaft. The axle bearings do not create any type of longitudinal stability, it's all inside the pumpkin.
