The "DA" plug is the one I mentioned. There's nothing exotic about it. It's just a 2-wire plug that allows you to complete the excitation circuit and turn the regulator on. People just invent fancy names as an excuse to overcharge customers for the same thing that can be done with a couple of terminals and 3" of primary wire or a connector plug clipped from a wrecking yard wiring harness.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!