The Ford voltage reducer is a mechanical/electrical device.  It functions much like the flasher for your turn signals.  The voltage can vary from 5.5 to 7.5.  An electronic regulator is a much better solution as it will supply a constant voltage although some electronic regulators mimic the mechanical regulators with a varying voltage output.  The first items on the Mac's link are required for each individual gauge you are converting.  I don't know anything about the other devices.

Jeff Petersen

Here's some from Mac's Auto  http://www.macsautoparts.com/ford_mercury_late/catalogsearch/result/?q=guage+volt+reducer&x=21&y=12                      Barry L.

It sounds like your regulator is shorted. The  input should be 12V output should be 5-6 V. The case needs to be grounded when you bench test it. I just went through this with my 57 Mercury.. I went to radio shack and bought a 2 dollar 12v to 5.4 v solid state regulator.. If you can solder small terminals it works great.

I converted my 54 Ford Wagon to 12 volt. Using what I think is a stock Ford instrument voltage regulator. I have two of these regulators, slightly different style but both behave in the same manner. , I get two issues.  Measuring voltage in is 12 and out is 11. 9. The wiring is hooked up correctly. When I remove the wire to the gages/output the voltage goes up to 12.
The other issue is when I mount the regulator to the metal above the kick panel the idiot lights flash and the fuel and temp gauge go to off.  When I pull the regulator away or let it dangle the idiot lights, fuel/temp gauges seem to work ok bu the idiot lights seem brighter then I remember. In looking at a 57 Ford Manual the regulator is mounted to the rear of the speedo pod. Not sure that is significant.