I believe there are some in the Group that can shed some light on this issue.
My 300 is fine, this is a 74 Dodge that I replaced the dash panel and gauges.
The ammeter gauge is out, a voltmeter gauge is now in place. This does not wire to the heavy red and black wires, that were connected on rear posts of ammeter.
My inquiry to the supplier was answered with " connect those two wires together, tape them thoroughly. Connect the voltmeter per Manufacturers instructions.
I have not connected the rand black, there is no battery in vehicle yet.
Is the supplier correct, that it is safe to connect them together?
They were connected to an internally shunted meter, OEM.
Keeping my fingers crossed,
Dave in windy VA.