Stuart, all 41-47 GMCs came with electric temperature gauges and senders. That was one of the differences between Chevs and Jimmys of that style. God knows why, but thats the way it is.
When I first aquired the truck I ran it at 6 volt positive ground. Then changed to 6 volt negative ground. And finally to 12 volt negative ground.
Yes, I did put the Runtz unit inline to the gauge as a negative ground vehicle would be. Same with the fuel gauge. I cant remember as its been months, but I believe when I switched to negative ground, I swapped the terminal connections at the Amp, Fuel and Temp gauges as required.
All parts worked on 6 volt negative ground.
Does that make sense now? My head hurts from thinking about it!
Thanks, Jeff
