It looks like a current P/N for the DIC switch panel is:
15947841
and they're not terribly-expensive. I've just ordered one, and will verify when it arrives. I also ordered the trim panel (15923338) for the truck with a DIC, and it was kind of pricy ($150, IIRC).
Hopefully we can soon get a functioning DIC on our PPV. Otherwise, I see no way to set the trip odometer on the thing.
Now if I can only find a factory black console for it, we'll be set.
Swapped out the dash trim piece and installed the DIC in the Tahoe last night. While it's kind of scary prying the trim piece off, everything did come off okay, and the DIC works perfectly!
The trim panel stretches from the little panel where the DIC switch goes to just to the left of the passenger side vents, and includes the center vents. There are a series of metal clips that hold the trim piece in place. There is a clip on each end of this trim piece, one on the end by the instrument panel, and the other just to the left of the passenger side vent. For the panel piece between the vents, which looks like a separate panel, but is actually all part of the whole trim part, has a series of three clips running along the top and bottom of the panel. These clips clip into the dash horizontally. That is, even though the dash is sloped, the clips are pretty much horizontal.
The center vent is also held in place with some plastic tabs that will hinder your effort to remove the panel even after you get the metal tabs loose. It just takes a little more effort to remove, I used my plastic pry tool along the top of the vent to get it loose, and everything came out in one piece.
Once you get the panel out, you can pop the DIC switch panel into the trim piece, then set the trim piece up to the dash, plug in the DIC into the harness, then pop the trim piece back into place. The palm of your hand is handy for doing this.
If you're considering adding this feature, I'd suggest doing it sooner, than later. If the plastic in this truck is like just about all the other GMs we've owned, that plastic gets brittle with age. It takes a fair amount of effort to remove the panel. I'd expect to see some of those clips staying attached to the dash if I had to remove the panel in a few more years.
Now, if the FedEx tracking site is accurate, The Big White Truck should be shoving our console out the back doors this afternoon.