Depends on the year of your truck but you need to find a rear view mirror with a camera looking thing hanging off the back (aims out the windshield). Some years have microphones built into the mirror, 17+ does not.
My truck is a big horn and had all the correct wiring, once I found the right mirror it was plug and play along with using Alfa obd to add the correct bcm settings. Not sure if other trim levels are missing wiring. Mine had auto dim from the factory so that might be the minimum you need to not have to deal with wiring
Rear view mirror part number for my truck was 68295862AA
You'll also need a new bottom cover so it has the opening for the sensor to look out.
I believe there is a thread on here somewhere with all of the rear view mirror part numbers.
The auto high beams work quite well, almost as good as the ones on our Lexus.
Sent from my Nexus 6P using Tapatalk