Well, that explains another mystery! When I had the cover off, there was a connector marked "Alternator". Not connected to anything, of course. But I guess that comes into play when you do a twin tank "alternating" setup.
Of course I was thinking "alternator" in the automotive sense
Anyway, looks like somebody in shipping just grabbed the wrong box.
I will try to call you this afternoon to see if you found out anything from the distributor yet.