1968 Barracuda with internal gauge régulator

+12 is normally fed to the fuel gauge on the lower stud were you see a new red wire landed above. The internal regulator converts it and sends +5 to the buss that feeds all three. You have to remove that +12 feed from the barrell and re-route it directly to the regulator. You also have to defeat the internal regulator in the fuel gauge to make it work. I opted to replace them all with modern resto replacements in lieu of modifying the original fuel gauge to accomplish this.

I also opted not to cut the factory barrell wire and just removed it from the Barrell and plugged into the blue feed wire to the new electronic regulator. If I ever decide to go back full original I can do so easily.

Normally there is a capacitor that also plugs onto the lower fuel gauge stud and is fastened to where I put my new regulator. It can be omitted when going electronic.

If you decide to bend the fuel gauge regulator arm to seemingly disable it, then connect the new +5 feed to the center terminal instead of where mine is connected. It has been done but not my recommendation. Remember the gauges are 50 years old and likely need to be replaced anyhow. How many times do you want to pull the dash or crawl under it?