I owned a GMT800 which I bought used and drive for nearly 100k miles.
Last year, I started a rather extensive search for another GM truck. Originally, I wanted a half-ton GMT900 and for a while I ignored K2xx. One fact I found was that the GMT900 resale value was quite high especially for the 6.2l. My criteria included 6-sp, 2wd, CCSB, & 6.2l which limited to '9 and newer. I did not want first year for the 6-sp, so it became '10 or newer; '11 and up were preferred. Avalanche 6.0l (extremely rare 2wd, only made in 2009 for 6.0l & 6sp combo), Avalanche 6.2l (very rare Canadian model) and Escalade EXT (AWD only) were also considered for their increased chassis rigidity and slightly less archaic rear suspension. The suspension combo, FWIW, was still more advanced in design than, say, my '12 BOSS 302. I was versed enough in GMT900 that I could differentiate the engine type from its tail pipe appearance or from a quick glance of the VIN.
GMT900 came in two different dashboard configurations. The more luxurious SUV dashboard on higher trim levels and the standard, "more flat" dashboard. I believe only the SUV dashboard can be equipped with a center console. Andy's '7 SLT has the SUV dashboard. Just like any full-size GM trucks for the las 3-4 generations, the option and package combinations become a dizzying array. Add special editions like Texas Edition and U of Texas Edition, determining the book values was a good-sized homework.
The problem with DOD appeared to be quite widespread. By deleting the VVT, Corvette cam (LS9 I believe) can be swapped in for a small cost. DOD can be also defeated using an electronic device plugged into the OBD port. Its effectiveness might come with a few minor consequences; can't remember anymore what they are. Another problem is heavy corrosion; so, search your truck in Texas or in Arizona; Alabama, Georgia, and Louisiana are ok too, but pricing is lower in the first two. Make sure that it was bought and driven there.
At the end, GMC had a Black Friday Sale with a 20% MSRP Cash Back which put a '15 K2xx in a very favorable pricing level. Let me just say that I got a total of 27% discount from the MSRP. A couple more grand and I could get a '15 over a '13 with very low mileage. In your search, pull a GM VIS report which should include service & transaction history and build sheet. Never assume the availability of an option or a package from the photos.
More questions, just ask. I'm sure I left things out as the search was nearly 6 months long.