Do you know what the amp rating is on your amp meter? Is the 78 amp alternator a newer Mopar replacement factory type or a after market one?
If Mopar type try reading the voltage at the output side of the alternator on the big wire going back to the battery with the motor revved up above 2500 RPM and see if the voltage output increases Is the alternator belt real tight or not? If not tight, tighten it up so it is
Let us know what you find