big volts

-If cleaning the VR ground doesnt do it, then perhaps this;
-It seems to me that the charge current is not getting back to the battery.
-Juice goes from alt to port"P" on the bulkhead connector, then to the #1 splice(somewhere under the dash),then to the ammeter, then back to the bulkhead connector,port"J" this time, then to the fusible link, then the binding post on the starter relay called "B", and finally to the battery.
-Getting back to the #1 splice;There are 6 wires spliced together in the harness there. Two you already know; the feeds from the battery and the alternator.The other 4 are feeds to; the ignition sw,the fuse box,the headlamp, and the horn.
-From the ig sw. RUN side; power is fed to the regulator and the ballast.

-Heres the thing; if everything is connecting properly, the voltage should be about the same everywhere in this circuit. Its all one long series circuit.
-Since the ballast is receiving a high voltage, that means everything from the alt to the #1 splice to the ballast is connecting.So the problem must be between the splice and the battery.But since it runs, that means it cranks, so power is obviously getting from the battery through the splice to the ig sw.
-So its a bit hard for me to understand how its possible for one end of the circuit to be at 16+ volts and the other end to be at 12.8volts.
-I tell you what;With engine off, measure the voltages at the battery and at the alt output stud.They should be close to the same, because they are pretty much opposite ends of the same wire.If theyre not nearly the same, I would do two things. First I would check for a pretty substantial off-draw.If none found,I would then check the following; the "J"port at the bulkhead connector(this is probably the number 1 problem spot on our old A-bodies),the fusible link,the binding post at the start relay,the ammeter connections,and finally, the #1 splice ( this splice super rarely makes trouble).
-Well I better not forget the battery itself.I suppose it could have an internal problem.
-Oh, in case you need to know; the "J"port is where the fusible link enters the bulkhead. I believe its the center connector, bottom right.And the "N" port is the same center connector, top left corner.
-Ive been wrong before, so I hope its the VR ground