I have now upgraded to the Petronix module in the distributor and a MSD coil. The yellow wire going to the stock coil is from the starter solenoid. Can I now leave this wire off since I no longer have points and condensor?

possibly, if the resistor wire has power while cranking the engine, you do not need the yellow wire, but it may be hard starting (because of the lowered voltage without the yellow wire)

but, because you dont have points and you have an mds coil, you could run full 12v to the coil from the fuse box (or cut out and replace the resitor wire) and then you will not need the yellow wire

You do need the yellow wire going to the starter. It supplies the voltage to the the coil. You will need the 12 volts to the coil at initial start-up. You can remove the resistor wire and replace it with a new wire that will supply the coil with 12 volts after start up.

so dave are you saying that the resistor wire doesn't have voltage when cranking?

It is my understanding that the starting circuit works by the yellow wire supplying 12 volts to the coil when the engine is cranking over. As soon as the key returns to the on position, the ignition switch then will supply power to the resistor wire cutting down the voltage to 8 volts to the coil. The reason is to lower the voltage to the coil to keep the points from burning out prematurely. If you remove the yellow wire then the coil will not get 12 volts to fire the engine when the key is in the start position.

thanks dave, i was unaware that voltage was cut from the resistor wire while cranking