In the 300TD, the self levelling box is near the rear axle and measures about 4 in by 4 in by 1 in with a lever attaching it to what looks like a sway bar. Also you should see a plastic jug filled with hydraulic oil at the right front part of the engine compartment. Check to make sure you have enough hydraulic fluid in the canister. Problems occur in the pump (mounted on the engine block), the self-level control (described above) or in the gas system that supplies air to the shocks. If you do not have the self level system fixed, your front tires will wear out quickly on the front inside tread<p>