You might want to add a wire form the battery terminal on the altenator to the positve side of the battery or starter relay,I think chrysler had the wire from the altenator going through the gauge before it went to the battery to charge and thats a long route. I had a 68 newport that would not charge much at idle and thats what I done and it improved the charging,being a 75 you should have the better charging system but if the gauge goes bad it wont charge and adding the extra wire will eliminate that problem. Jeff