I have been bogged down with some other issues not related to the truck right now. Sorry that I have been stalled out. I do plan on giving this another try in the next few weeks if I can keep the wolves away from the door. I am leaning towards the idea of buying another starter and trying that as suggested above by Kurt. That was actually a thought I had a couple of months ago but decided to pull the engine instead. Now I can go back to that in view of what I found comparing the two engines.
As I have said in one of my earlier posts, I am certain that the flywheel is correct based on testing with the 12 volt starter that didn't like the flywheel. As far as I know there are only 2 sizes of flywheel... one for the 6 volt and one for the 12 volt. I did measure the starter gears on both starters and confirmed that the 6 volt has the larger diameter. That's about all I have right now...