A used Mercedes-Benz transmission is an original unit sourced from a donor or salvage vehicle. Mercedes-Benz models commonly use 7G-Tronic or 9G-Tronic automatic gearboxes across platforms including the C-Class, E-Class, GLE, and S-Class. These transmissions are precision-engineered and require accurate matching of the vehicle model, production year, and software version. Used units vary in condition based on service history and mileage. Buyers should request documentation confirming the unit's origin and testing status. Installation of a used Mercedes-Benz transmission may require dealer-level programming to ensure compatibility with the vehicle's electronic control systems and transmission control module.