I would need a pic, Chrysler has not used an external resistor for quite a while, was used on the carburated cars (2 wire and 4 wire), they were white and about 3" long and 3/4" high with a hole in the center.
I could be wrong about what they were used on but I have not seen an external resistor since I had my 72 Duster. The 2.2L/2.5L used an internal resistor and if you go aftermarket performance coil they usually tell you if you need to install a resistor for your vehicle.
Check the manufacturer's web site for the coil you are using.