Autometer makes gauges in various specs to match different manufacturers (ohm rating empty and full). As a start, what is your guage rated? MOPAR is +/- 10 ohms full and around 78 empty. I can't find the exact specs in my FSM right now but this should get you in the ballpark.

Corrected "empty" ohms. link attached

https://board.moparts.org/ubbthreads/show...rue#Post6511431