2003 ML350 - I need the trailer hitch 7-wire connector plug, the plug into which the trailer wiring plugs. The MB installed plug is broken and MB no longer supplies parts for the factory installed hitch. The factory unit is a standard circular 7-wire plug to the trailer and the connection to the factory wiring harness is a rectangular plug. Can only find after market plugs requiring me to cut off the factory rectangular wiring harness plug and connect loose wires into the after market connector.