Since we got our '18 Tahoe last year I have really missed the auto dimming mirror that our Honda Pilot had.
So as soon as I bought the '14 Silverado earlier this month I knew this would be one of my first upgrades.
I ordered a used mirror on ebay GM 13584893
Then ordered a premade harness from Phil at
https://harnessdr.com/
It was easy to install and works great. No more pressing the Onstar buttons while trying to adjust the mirror.
Next I will be upgrading the outside mirrors from the stock DL8 to the DL3 mirrors. This will give me power folding, puddle lights, turn signals and auto dimming.