67 Cuda instrument voltage regulator

Troubleshooting the reason why my gas guage and oil/ water temp guages don't work. Couldn't find the voltage limiter that is supposed to be plugged in to the back of the instrument panel. Removed dash and found that the 67"s have a built in limiter inside the gas guage. Tried to repair the unit, but didn"t have any luck. I've installed aftermarket oil and water temp guages, but woild really like to get the gas guage working.
I've read numerous articles on converting the system over to a 5 volt regulater and heat sink, like you can buy at Radio Shack. But these articles refer to the models witha plug-in limiter.
My question is, have anyone run into this problem, and what success, if any, have you had in resoving this. I have the parts to do this, but it will take a little bit of engineering with the current gas guage. Thanks in advance...Larry