clonk from the rear.... [Expired Topic]

My 1999 diesel Suburban has a clonk in the rear when making a sharp turn to the right at low speeds and no load in the rear, (no passangers).
Today when I removed the right rear wheel, and the break drum, I noticed that the rear axel moves in and out a little, maybe 1 mm or little more, and creates exatly the type of sound I hear when making a right turn. Any idea how this could be remedied? Expensive?