I went to the junkyard and bought two OnStar Autodimming Mirrors with Compass, because for $4 I didn't want to risk buying a dud and having to drive there again. And it's fun to take parts out of junked cars! So I have a spare for sale. It looks like this: viewtopic.php?f=30&t=45247&p=514289#p514289
The compass is a separate module that attaches above the mirror, or you can relocate it to the passenger side if you like to have your mirror up high like us tall people.
If any GenVibe member wants it, just pay the shipping.
I'll even include 12 inches of wire and connector you'll need to insert at pin 13 for switched 12 volts.