They should all be wired for the switch, I got mine at Amazon:
https://www.amazon.com/gp/product/B00N48KATG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
The switch is cheap enough, but the trim piece is not that little section, it goes all the way over and includes the vents. I searched forever for the mythical used/cheap one, while my switch was plugged in and working, but just hanging out of the trim piece. I then finally figured mine is worth nothing, and took a shot at cutting it.
http://www.tahoeyukonforum.com/threads/finally-opened-it-up-and-stuck-my-dic-in.98879/
There are various numbers floating around for the trim piece, 20935584, 15923327, 15923338, depending on color, and new or old numbers.
They go for about $160 with the DIC switch cutout, and are worth nothing without the cutout, so you have nothing to lose by taking a shot at it.