Dimming Rearview Mirror Harness

I am thinking of geeting a dimming rearview mirro with the tem gauge. Suspect the required wiring harness is in the roof of my 2004 LT version. Can anyone confirm?

Thanks!

TB55123

In all of my experience adding stuff to these trucks, I have yet to have the wiring for options in place already. I've had to run all new wiring every time I have upgraded something. I am adding the compass/temp mirror to my truck as well...and no wiring :(

Only exception to this has been anything airbag (SIR) related. All of that wiring is in place....