One of the things I inherited when my dad died (a year ago), is a GPS unit. It is a Sony. It is a very great device.
I wanted to hook it up in my bus. My bus did not have a 12 volt receptacle.
I was going to use an old receptacle, but I did not have the connector to connect the positive terminal.
Feeling somewhat disheartened, I started to put my tools away when I realized I could MacGuyver a socket.
I remembered that I had a splitter for 12 volt sockets. Plug one end into the lighter receptacle and you had two sockets.
I cut one of the sockets. It has 8 inches of wire. I have many terminals with which to connect to wires.
I connected to one of the many circuit breakers located on the panel to the left of the driver's area. Many of those circuits have been rendered inop.
I grounded the neg. wire to the metal of the bus. I used an Adel clamp to hold the socket.
I now have a socket for the GPS.