Charging issue

The NEG reading is simply the way the meter is hooked

.66 is quite a bit of voltage drop

Your car is a what, a 66? So it feeds the ammeter through the bulkhead CONNECTOR as opposed to the older separate feeds?

The voltage drop can be anything in the feed path from the battery, through all the connectors, to the point that feeds the regulator, IE the regulator IGN terminal.

So your feed path (I believe) is battery---fuse link---bulkhead connector---ammeter---in harness splice---ignition switch connector--through the switch---back out the switch connector (on dark blue "ignition run" or IGN 1 --- back through the bulkhead connector !!!AGAIN!!! and finally to the ignition system, regulator IGN terminal, and "other stuff" on newer cars

So ANY bad connections in that path, either the connections or the switch, can cause the drop. "Some of us" have gone to relays under the hood to feed headlights and switched loads for that reason.

IF YOU HAVE the older "round back" alternator you can benefit from buying a newer "square back" (72? and later) alternator, as they put out more at low RPM.

You can use the newer isolated field (incorrectly called "dual field" with an older regulator by merely grounding either field terminal, but this might be a good time to add ONE MORE WIRE and convert the system to the 70/ later system.

Do NOT allow a rebuilder/ parts store to sell you an older "round back" alternator

Roundback:

http://www.forabodiesonly.com/mopar/showthread.php?t=201739

Squareback at bottom