Started it up at work this afternoon to go home and immediately noticed ammeter was going wonky - wild swings all over the place, showing both charge and discharge, but more towards charge (right) side.  It was worse when engine was cold and fast idle was on, but all the way home it still had some weird random swings that weren't tied to any increase in electrical load or engine speed.  In it's stable position while driving it was slowing a slight charge, like usual.  Still doing it at home so I put a voltmeter on the battery posts.  It would do different things at different engine speeds, but most voltages I saw were low to mid 14's.  At a constant throttle, volts varied up to .2 volt, not steady at all.  Got better at higher RPM's, but still varied.  Engine off, but key in run, shows steady slightly discharged ammeter and steady voltage, all as usual.  

Check the connections on the back of the alternator....is sounds like you may have a loose connection either there, or at the battery...or the main ground from the battery to the chassis. If all of that checks otay, it may well be a flakey regulator, but could also be a goofy meter(gauge), or connection on the gauge.

Thanks, Joel - you may be right.  That two wire connection (big red, small brown) has given me trouble before.  I unplugged it and noticed there was a crack in the insulation of the red wire.  Taped it up for now but will be ordering a new connector with pig tails in the near future.  Also one battery terminal was just slightly loose, but I don't think that was it.  We'll see tomorrow or Wed, depending on when I drive it next.  

There's a chance that you may have a wire somewhere that is shorting out intermittently...not a full, direct short, but maybe a wire with bad insulation that is touching up against something while driving just enough to cause a slight "zap". Depending on how bad it shorts, and what it actually touches, it could cause the gauge to show a minor/major overcharge, or a minor/major discharge....

This is a far chance, but see if your positive battery cable up under in the tunnel along the drive shaft is rubbing the drive shaft as it rotates. 

Drove it today and ammeter was steady.  Looks like I'm back in business.  I think the big red wire in the two wire alternator connector was the culprit.  Insulation is cracked just above the connector.  I think I can buy just the connector with the two pigtail wires sticking out about 3" or 4"?  Wouldn't want to replace the whole charging system harness for that.  Or I could just wrap it with tape real good like it is now....

Check with Lectric Limited, Dave....they may have a the pigtail connector for that, if you can't find one locally.