Voltage limiter

I have a 1966 Barracuda with a bad fuel, temperature and oil pressure gauge. I did some research and found that the voltage limiter is in the fuel gauge and it is supposed to bring down the voltage to 5 volts for all three gauges. I am getting a steady 12 volts at the temp sensor and the fuel sending wire. According to the service manual I should be getting fluctuating voltage that will average out to be around 5 volts. There is a way to disable the 12 volt feed to the fuel gauge and install an external voltage limiter. Could anyone walk me through that procedure? I saw pictures but I am not sure what is being done. Especially in the fuel gauge disabling the 12 volt feed. Thank you.