Ammeter with shunts are specific to be used with a matched shunt. They usually are sold as a set.

Mopar used this system since 75/76 and even could be used from a later model ( studs gap is the same ) but would need to get the shunt wire from the same car too.

I have a 78 F mody ammeter I'd like to use on my car just changing the face, but have no idea about how much must be the resistence of the shunt on this to convert my car on a shunted system, and by now have no found literature about this, maybe just getting a harness from this car with the shunt intact ( have no idea if I could get the shunt wire from another Mopar yet )

78 LeBaron ammeter