Which guage or both ?

redfish, checking the schematics in both the 1977 and 1978 Dodge factory service manuals, neither of them shows any "external (ammeter) shunt". I would suggest that you direct your question to slantsixdan. Why don't you ask him to point out where the alleged "external shunt" appears in the schematics?

Yes, there's a shunt, all right, but it's in the ammeter, not in the engine compartment as Dan claims.

The sine qua non of the argument is the very well-known fact that Chrysler ammeters burn up if the connections are poor. The only way this could happen is if the ammeter carries a large amount of current. If there were any external shunt, the ammeter wouldn't carry very much current and therefore wouldn't burn up when the connections degrade.

Moreover, using a so-called "external shunt" in the engine compartment, as Dan claims, would be extremely poor engineering practice and would cause electrical fires if the shunt ever failed. This is because if the shunt opened, all the battery load current would try to flow through the ammeter circuit, which would not be designed to handle so much current and would overheat.