[JSeery]

Should be around 1.5 ohms and supply somewhere around 6 to 7 volts to the coil. If you are using a starter solenoid with the connections on it the best set up is "S" to your start switch/ignition switch and "I" to the coil. This will put 12V to the coil during startup and cut off with the starter. The ignition post from your ignition switch should go to the ballast resister and the other side of the resister to the coil to power it at around 7v in the RUN position of the ignition. So in START you have 12v to the coil and when you release the key to RUN position you have 7v to the coil. I don't know about a source, most older Chryslers use them.

Here’s some commonly available automobile ballasts available from NAPA:
•#ICR23 – 1.20 ohms
•#ICR11 – 1.35 ohms
•#ICR34 – 1.40 ohms
•#ICR37 – 1.60 ohms
•#ICR35 – 1.80 ohms
•#ICR13 – 1.82 ohms

NAPA* Echlin* ICR11 (1.35 Ohms)
NAPA Echlin ICR23 (1.20 Ohms)
NAPA Echlin ICR34 (1.40 Ohms)
Lucas* 3BR (1.3 - 1.4 Ohms)
Mopar* DCC-4529795 (1.40 Ohms)
Accel* ACC-150250 (1.35 Ohms)
Standard* RU-4 (1.35 Ohms)
Standard RU-23 (1.20 ohms)
Standard RU-37 (1.40 Ohms)