The 2003 cars carry a specific risk of the radiator internally leaking coolant into the transmission, causing damage; commenters call the radiator the number-one preventive replacement on 2003 models and advise checking the coolant reservoir for oil before buying. Later cars are not flagged for this.
2003-only radiator coolant-into-transmission leak
Mercedes-Benz E55/E63 AMG (W211) · buying