I sent the Gentex 50-GENK6A mirror back to Mito Corp since Mito Corp could not deliver a wiring harness patch cable to make the older style connecter on the mirror connect to the new style connector present in the 2010 Camaro. I waited a LONG time for this cable and they were still several weeks away from having one.
I then checked with three different Chevy parts departments to confirm what part number was correct for the OnStar capable auto dimming mirror found in the 2LT/2SS Camaros. It is 13503048.
I ordered the 13503048 mirror from gmpartsdirect.com for a total of $103.60 (shipped). I just received it today and installed it in about 5 minutes. I pulled the Camaro out of the garage and tested the OnStar button and it worked.
I pulled the Camaro back into the garage and closed the garage door (to simulate night time). I used a flash light as my "light source from behind" to see if the mirror did in fact "dim". It did.
If you have a LS/1LT/1SS with a flip mirror, you can purchase GM mirror 13503048 to get the same mirror found in the 2LT/2SS Camaros.
The auto dimming mirror is "bigger" (height) than the flip mirror, but only by a 1/4". It really didn't seem like a huge change (to me).
So there you go....