Ok.... now whats going on?

[BIGSHCLUNK]

So I get my fuel leak fixed, so of course something else has to go on...  Amp meter has been converted to volts. Regulator is a few years old, but very low hours of use. What is the cause of the jumping? This seems to only be an issue at idle/low RPM. 
https://www.youtube.com/watch?v=qBrZ69KSqhg&feature=youtu.be

[Chryco Psycho]

Do you have a spare regulator to plug in & try ?

[BIGSHCLUNK]

I'm sure I got one laying around the shop someplace......

[brads70]

Ground?    Maybe gauge has bit the dust?

[dodj]

Hmm.  I wonder if it does that with the alt disconnected.  Kind of makes me think it is the gauge because i don't think the stock gauge can respond that fast to actual changes in current.

[BIGSHCLUNK]

Had the gauge converted @ RED LINE a few years ago. I don't understand how it does that yet straighten out with more RPM. I did find another reg this morning, so I will swap it out.... stay tuned.... 

[dodj]

Had the gauge converted @ RED LINE a few years ago. I don't understand how it does that yet straighten out with more rpm

Sorry.  Missed that in the first post.  A bad connection through the bullhead connector could do that to a volt gauge.  Or the back of the alt more likely.  Engine shakes more at idle.