Thanks, guys. The leak is not at the sides but at the pinion pearing. It was full and not leaking when I bought it, but apparently the differential has been run dry in the past because the gears now have that terrible clunking and grinding. The pevious owner probably re-sealed an already damaged differential, it seems to me. Given that the axles might now be bad, as you have pointed out, I would feel much better replacing the rear end rather than repairing it. I am in Atlanta and would love to get a line on where I could get one.