I just installed a new MSD ignition, 6AL ignition box, distributor, and coil on my 69 Roadrunner. I am have a hard time finding a constant 12V wire to power the ignition box. All wires I put a volt meter on either drops to 9V or less when cranking, or show 12V when cranking then voltage drop after I stop turning it over. I can hook a jumper from the battery to the 12V on the ignition box and the engine fires right up and stays running, but won't shut off when I turn the key off (I have to disconnect the jumper from the battery) which I understand. I am not using the ballast resistor as per the instruction from MSD. I rewired the whole car with a Painless wiring harness about 10 years ago and all has been working fine. Can anyone suggest a wire that stays constant 12V thru the ignition switch?