I have a 70' dodge D100 that I recently took the motor out of and re did all the gaskets on, when I put the engine back in it wouldn't start, it turns over and after a while what we did was pulled the coil plug from the distributed cap and brought it close to a ground to see if it would spark, it rodent so we measured toevoltage coming from it and measured 5volts while the key is on 7 when it was turning over and the battary was putting out 12 volts could it be my ballast resistor?

 

You still have breaker points igntion? Can you tell if the points are opening/ closing and conducting current?

Clip your test light to coil NEG and crank the engine USING the KEY not by jumpering the starter relay. The light should flash on/off if the points are opening.

RE-measure the coil POSitive terminal

1 Key on

2 Cranking engine using the KEY. You should measure close to "same as battery" and in no case less than 10.5V

Does it seem to crank over OK?

If you are getting good cranking voltage, if the points are opening/ closing, try changing the condenser, and then the coil.