Thanks to Gary (for making the adaptor and posting his instructions) and Shawn (for answering several e-mails regarding the installation) I've got a working GM electrochromic mirror in my 2.3. It's great!! I would recommend it to anyone that drives top-down (which is all of us, yes?). The annoying ghost images during the day and the bright sun in the late morning and early evening are completely eliminated. It wasn't a snap to do but it wasn't too bad. Certainly worth the effort.
Now for the question. Does anyone know what the part BMW 1439344 does or goes? It's a white plastic "tube" that has a 90 degree bend, an inlet that's rectangular and an outlet that's semi-circular. Fell out when I took the glovebox out and I can't figure out where it goes. About 1 1/2 inch by 1 by 1/2. Seems too small to be part of the ventilation system.
Thanks for any leads.