Don,
I don't know the answer to this conundrum! No 10SI came with a regulator that allowed single wire use(stock). There are aftermarket brand regulators available that rebuilders utilize that will allow single wire use OR three wire connection. The rebuilders often stock only this one regulator as 'one size fits all'.
If you were to purchase a alternator from a auto supply house and it was called out for application, I don't know if it would have the 'one size fits all' regulator...maybe that's all they make these days.
If your regulator isn't the type capable of single wire service then your alternator isn't going to charge until DA#1 is connected and energized. It's pretty easy to diagnose but we haven't seen any feedback from the folks asking these questions.
That's about all I think I understand on this topic...
Stuart
