What's the best way to replace the Cluster Voltage regulator?

I just pulled my 73 wiring diagram (it may be similar to yours) and it looks like all of the lamps are powered from the headlight switch. The ammeter looks to be the measurement between the alternator and the starter relay. All the actual cluster power comes from the alternator into the headlight switch (I could be reading this incorrectly, though). If your fuses are setup the same as mine, fuse 6 looks like it feeds all of the gages (not the ammeter), the oil lamp, the brake lamp, and some seat belt relay stuff.

The extra prong on the voltage limiter may be the ground for it. I don't remember where mine connected, but I think it just rested on the non-copper portion of the cluster.

When you get voltage on both sides of the ammeter, do you get positive on one and negative on another? The meter is setup to read "negative" amps (just a direction, I think) when the car is running on the battery and "positive" amps when the car is running off the alternator.

I suppose it could be a bad voltage regulator, but I don't know if it is common to blow a fuse if one goes bad. Three amps isn't a whole lot, though, when you consider your alternator is probably putting out more than 60 (if it is a newer one).