You bought the truck with that mirror? I can find them on ebay, but they look like they need a special plug to work (vehicle specific).
I bought one out of a 2003 Saturn Vue for mine. The wiring looks specific, but it's not. It's a pretty simple mod., even mounted onto the existing button on the windshield. You'll have your 12v power, ground, two wires for the Temp sensor, and I believe there is one additional wire for disabling the auto dimming when in reverse . I never connected that one, didn't really see the need. The temperature sensors are universal to most GM cars, you can find them either on e-bay, or even order one from a GM dealer. I didn't get one with map lights, I kind of wish I had, but I guess it's ok without them. They are a little more expensive with the map lights, and I very specifically wanted the temperature. Mine displays the temperature and compass heading simultaniously. Also, FYI, mount the temperature sensor in front of the radiator for the most accurate reading.
Anyway, I had a question about the overhead consoles. I've really thought about doing this, but I really don't want to cut the headliner. Is it possible to mount one basically ontop of the headliner, and drill through the headliner to mount it. I wasn't sure if that would work or not. I'm not sure I'd do it if I had to cut the headliner.
~C-Dawg