How to run a modern GPS in your A, submitted by Frank N, based on information from Tom Wesenberg.
I got the information on hard wiring the GPS in a 6 Volt, Positive Ground system from Tom Wesenberg, the Fordbarn electrical guru. It is very simple, but you must insure that the socket you use is entirely insulated. Tom use a hand grip to insulate his socket and I used black, plastic electrician's tape. I bought my socket at Advanced Auto Parts and the beauty of that is that the socket comes with a mounting bracket (be sure to insulate the bracket too if you go that route).
As for the wiring, I used 18 gauge, multi strand wire from Radio Shack. At the end that connects with the socket I affixed female connectors that will slide over the socket's bayonet contacts. At the other end I affixed the appropriate size O connectors. I used black (+) and red (-) wire. Fasten the black (+) female connector to the center contact of the socket and the other end to the starter mounting screw (small O connector). Fasten the red (-) female connector to the outside body contact on the socket. The other end of the red wire has a larger O connector that goes over the post of the fuse block. The wires run down the steering column and are neatly taped to it.
That is all there is to it, but remember wiring it in this manner will not turn it off when you turn off your ignition. So if you leave your GPS plugged into the socket it will continue to drain the battery even if the ignition is off.