I have a 69 Mach 1, 351W Mallory Unilite distributor, MSD Blaster 2 coil. The problem I have is that I'm loosing spark in the cranking mode. I have spark when the key is turned on loose ignition during cranking & then the engine attempts to fire when key is released. I have replaced the ignition switch, coil, regulator but not the solenoid. There is power to the coil with ignition on, power from coil. I seem to remember hearing of this problem before & it was a simple fix that had to do with a wire from the starter, alternator or ? Any help would be greatly appreciated before it goes for a ride on a flatbed!