Cranks but won't start. Unplug ground at field spade on Alternator and it starts?

"Spade that I ground to alternator body: 5.9 ohms"

No understand LOL. You ungrounded it? Is anything connected to the opposite field connector?

" Alternator field with alternator ungrounded at other spade: 3.3 ohms"

You are going field to field? This is about right. The fields vary as to battery current draw, there is a procedure in section 8 to check that. Some newer/ heavier alternators draw more current. I could be wrong, 4-6amps? So Ohms law is I (current in amps)= E(volts) / R (resistance) So 12V divided by 3.3 is somewhere around 4A so that should be OK

You want to make sure with both field terminals isolated from ground, that both field terminals measure open (infinity) to ground (the case)