Agree that isolating variables is the best path forward.
For now, I have the old resistor back on the truck.....and I am going to get a proper 12v coil designed for use with an external resistor.
From there, I will see if I have voltage readings at all the specified points that are considered more textbook. And if they are, I will go back and re-visit plug gap, dwell, timing, etc.
This whole mess started with a a sudden no-start problem and verified no-spark symptom a few weeks ago. In spite of all the weirdness with my coil and whatever else, the truck has run pretty well every time except that one. I may well have been chasing some ghost all along....but at least I finally got around to looking at the coil the other dude installed.
