Alternator Question?

I think you'll find that upper spade terminal is also a ground. It's not like the other ( a brush holder ).
So... closed field. Green wire from regulator to the field terminal ( brush holder ) and ground(s).
If your harness has a blue and a green wire to alternator, that is isolated field system. You would need a different alternator with 2 brush holders.
A split lock washer would fail in the adjust slot without a flat washer.