No spark when cranking

Ok so this is a problem I have been trying to fix for over a year now and I finally stumbled onto some additional information.

1974 Swinger /6 with 5 pin ECU. I have checked wiring, cleaned/sanded/star washered the ECU and Voltage Regulator. I have replaced, ECU, Dizzy, Voltage regulator, alternator.

What is the minimum voltage needed on pin 1 of the ECU?

Blue wire voltage on the 4 pin ballist resistor is:
11+ volts in Run position.
5.5 volts in Start position. No Spark.

What can be pulling down the voltage on the Blue wire so drastically?

If I pull the Blue wire off of the Alt. or disconnect the voltage regulator I have 8 to 9 volts to the ECU and I have spark the car will start correctly.

Thanks
Ron