W I D E swinging alternator guage

[Kern Dog]

My alternator guage in the 70 REALLY swings to the 40+ right side when the engine is first warmed up.  I changed the voltage regulator and the alternator seems to charge slightly less, but it still runs into the 30 amp range. I probably should put a different guage on it to verify the truth of the stock one.
WHO makes a decent voltage regulator? Are they still available from the dealer?
Thanks, Greg

[b5blue]

Try this, fully charge the battery with a battery charger. (Not the car's alt.) Take a voltage reading. Is it 13.5 or more volts? If no battery is weak. If yes battery is OK. Get a power plug of the type that plug into a cigarette lighter socket and wire it so you can hook it to a meter. Set the meter on the dash and read voltage off the lighter socket. Now your reading working voltage to car and AMP draw to the battery recharge wire.(From the gauge.)  Tell us the readings. 

[Nacho-RT74]

a tipical sympthom of a lousy connection on charging line, specially if needle goes back and forth with gas pedal.

does it show discharge in some moment ?

[Kern Dog]

B5 Blue: good advice.
I tested my battery and found that it was at 11 volts! I've been working on a stereo install, followed by brake work and all the time with the doors open must have slowly drained the battery. I put the Optima battery on a trickle charger, then I tested another battery and found that it was at 12.5 volts. In the car, the alternator guage reads closer to 20 with the second battery. I didn't think that my battery was THAT low!
Thanks guys!
Greg