I need the proper wiring connection for the fuel guage sending unit. I have read that the resistance of the sender is to be 82 ohms. I used a decade box in series with the two wires going to the guage and got no readiing at any value. The guage does go to 100% when I short the two wires together. I have contacted many suppliers and was told there are no 'factory' senders available - 'build your own'. Any ideas?