My ammeter recently started pegging toward the discharge side of the gauge. It takes a while for this to start up but I've noticed you have to be driving for a while before it will start doing it. It just shoots over to the left two or three times real fast and then settles down. Definitely gets worse the longer I drive. The other day, it kept doing it after I shut the engine off and even after I disconnected the battery. It's accompanied by a clicking sound that is coming either from the voltage regulator or the horn relay. Can't really tell which. Battery is between 12.6 and 12.9 volts at rest and somewhere between 13 and 14 at fast idle. Just wanted to find out if anyone has had similar happen before I start digging into it.

1956 Chevy 3200