Anyone know if the '07s (or 05-06 for that matter) are prewired from the factory for the auto-dimming rearview mirror even if not originally equipped with it?

If it isn't, you can always take power from the map lights.

There is a lot of good info on better mirrors around this site...

i tried searching for extra wires up there, and there was none...

As far as I know.... no. When I asked for the option on the truck when we got it, we were told that it takes them a bit of time to install since they have to run the wiring for it.
When I installed one myself, I didn't find any factory plugs up there either.

Thanks for the quick replies fellas. Much appreciated.