If you have upgraded to Electronic Ignig; they wont work worth crap! Upgrade that pos and READ the notes!
There are a number of reasons one might want to upgrade a per-1970 system to a transistorized voltage regulator. The list of reason include
Chrysler recommends you switch to a transistorized VR if you upgrade to an electronic ignition from a points style ignition.
If you have to buy a new voltage regulator, the difference in cost is only about $5-10 more for the transistorized unit. Not to mention, the quality of replacement early style VR's is spotty.
The transistorized VR will have a longer life.
Below is a diagram describing how to install a 70 and later Voltage Regulator on a sixties mopar.
charging system overview