By all means start at a dealership. They probably have several sets laying around to sell you. Yes, it is the red 10-pin plug. Any dealer will know what you are talking about with just that information.
Go to WWW.aomci.org then to the Classified section and post your request in there. Good bunch of folks and someone in there will have what you need. I would get something from the later 70's on up. Anything with the 10 pin.