[longhorn335]

^I ran into the exact same issue. What I did, is I removed the ring shaped cover plate on my old mirror, and those 3 pins that form a triangle. I drilled the bolt holes on it a little to make the hole wider, that way you can fit it on the new mirror. On the new mirror, you also need to grind/saw off that little protruding piece so the plate can sit flush. Then assemble it with the 3 pins, then the plate, and glue. I used gorilla glue. Hope this helps.
One downside is, I wanted to sell my old mirror, and now is incomplete, no big deal, since the new mirror w compass and homelink was cheap