Okay. Got 'em. There's a third wire which, according to this option and this option, means that it they do have "BY IMPEDANCE WITH THIRD WIRE SPEED SENSOR (TACH OUTPUT)" (copied from their site). Interesting? I dunno.... can you guys do anything with that? I'm guess I can just cut that wire off...

So. I'm going to go take the empeg apart and take some photos of where I gather I should be soldering things in before I go ahead and do it so I can make sure I'm doing it right. Be back in a few.