Jeep Strokers

I have a VDO ammeter installed on my CJ-5. It has a '69 Chrysler alternator (with external regulator) in it.

It charges fine. The trouble I have it that after it has warmed up, the needle will jump, rapidly & violently, from charge to discharge--

I recall hearing that there is a way to cure this by briding the terminals or the terminals to ground, witha capacitor.

Anyone have the skinny on this, please??

I don't know, but I would check the connections first, between voltage regulator and battery and alternator. Spikes like that either mean a bad connection (it can go worse when hot) or a faulty voltage regulator (wich also can go bad when hot).