Getting ready to install speedhut gauges in my 73 challenger with standard dash. Here's the wiring diagram I drew up, tell me what's wrong as I'm sure something is...
I'm not sure why the volt gauge would need four wires off of it. It should just be switched 12v, ground and lighting.
What is the "fuel sender" ground wire doing for you? Are you using a factory sending unit?
The grey wire for lighting, the "speedhut lighting dial" does what? I assume if it's some form of dimmer it would need to go before [in series] all of the other light circuits and not in parallel to the circuit. But that's a guess, i'm not familiar with it.
Does the speedo need constant power for keeping settings?