Reply to "Battery Issue?"

If I were you I'd cut my losses and go to this.

http://pantera-electronics.com/gm12sialternator.htm

I've seen Cobras do that with the Smiths gauges but the Pantera not that crazy of a fluctuation? Look out for that gauge too if it's an original.

They have been known to short out and the battery grounds to the chassis through it.

It will melt more than the gauge if it happens and there is no way to stop it.

I think your issue is just a too small of an output on the alternator. You need to go to either a 100 or a 130 amp alternator.

Lots of folks have had great success going to the GM one wire set up.

I personally have a 130 amp alternator. Shows no issues at idle or anywhere else. It can be a little noisy at times though.

The one wire will eliminate the need for the remote regulator. It will have an internal one.

Eliminates some of the guesswork usually but I have used them and you can short them internally so I'm not sure if it's an upgrade with the internal regulator or not?

The internal regulator is really intended to be used with a car with a "whole car fuse". Having said that, by the time the fuse blows, the alternator is usually blown also.

The problem with the external regulator is that it has internal points in it similar in thought to what a distributor has.

The points can burn and/or carbonize and also can oxidize from the moisture in the air.