72 Dart Swinger Fuse Blowing (New to Older Cars)

Im using a 30 amp inline fuse in my demon and have had no issues...... Untill the voltage regulator went bad and she was overcharging almost up to 18-20 volts.
#-o

How did you diagnose the voltage regulator? Did it start blowing fuses or was there some other indication?

I'm stumped with where to start if it isn't the voltage regulator.