Finally got an assistant and a dry day to get back on this headache. So I'll list out the info and see what we all agree is the issue. Still same symptoms - all electronics working / turn key / lights/dash go dark / no crank / one click at the starter relay on the firewall / nothing else
First number is key in, second number is under load/key start
Battery - 12.21/12.5 - voltage goes up when key is turned.
Starter points voltage drop from battery
s-terminal - .42 / .05 (red lead battery + post / black lead on s-terminal)
b-terminal - .00 / .00 (red lead battery + post / black lead on b-terminal)
m-terminal - 12.21 / 12.5 - (red lead battery + post / black lead m-terminal)
ground - 0.01 / 0.00 (red lead battery - post / black lead starter body)
So the starter circuit looks okay, the power supply looks okay, so the starter itself is the culprit??? I don't know why, but my brain just won't absorb a basic understanding of electronic circuits.