Uncleb, we're practically neighbors. I'm in Santa Rosa.
When I first got my '36 Chevy pickup in 1965 it was all original and I foolishly made a rat rod out of it. Part of that was converting it to 12 volts. The dad of one of my friends worked at Lockheed and fully understood instruments like my gas gauge.
The short version on the gas gauge was that he told me it would work on 12 volts without any resistor. I know he was right because I ran it on 12 volts as a daily driver rat rod for about 50,000 miles before restoring it back to original in the early 70's. If you want to know WHY the voltage made no diference I'd be glad to give you the explanation he gave me.
A lot of unnecessary adaptors are sold. Here's another example. I moved to a rural area with no natural gas hookups in 2001. Adaptors are sold to "convert" stoves from natural gas to propane fuel. In reality, all the "conversion" required was adjusting the metering screw on each burner tube to get a neutral blue flame!
