49geezer,
I'm lost on this one. If you stick a 261 Chevy into your GMC, why not just put the original GMC sending unit back into the Chevy engine and no one will be the wiser.
Is your actual problem getting a 6 volt gauge to read properly after you convert your system to 12 volts. Does installing a voltage reducer ahead of the temp gauge gum up the works and make the gauge inaccurate?
Stuart
