I wanted to put up a good visual reference for these model years:

2015 Chevrolet Silverado LTZ 3500 HD Double Cab/Long Bed 4x4:




This one has been verified by the factory sheet on the dashboard VIN information that I have read off here.

Please feel free to add necessary information for this reference information here.

2015 Chevrolet Silverado 1500 Regular Cab Long Bed WT:




2015 Chevrolet Silverado 3500 HD Crew Cab Chassis WT as incomplete:

I found this at the local Kroger parking lot today.

Chevrolet Silverado Double Cab/Regular Bed LT Rally Edition 2 (Observe):

Chevrolet Silverado Double Cab/Regular Bed LT Rally Edition 2 (Reverse):

2015 Chevrolet Silverado LT Double Cab/Standard Box 4x4 Rally Edition 1

Observe:


Reverse:

2015 Chevrolet Silverado LT Crew Cab/Standard Bed 4x4 Texas Edition

Observe:


Reverse:


Script:


Note: I made a mistake listing as Texas Longhorns Edition where it is actually Texas Edition. Sorry

2015 Chevrolet Silverado WT Double Cab/Standard Bed 4x4 Black Out Edition

Observe:


Reverse:

2016 Chevrolet Silverado 2500HD LTZ Z71 Crew Cab/Long Box Custom Sport Edition Observe:


Reverse:

You can see my mother's 2005 Toyota Sienna at the background at the right

2016 Chevrolet Silverado 1500 WT Regular Cab/Standard Box Black Out Edition Observe:


Reverse:

my car likes to sneak in pics too...

I was able to pick up the sub-series of these GMT K2XX series from Wikipedia:

https://en.wikipedia.org/wiki/GMT_K2XX

GMTK2RC: Regular Cab Chevrolet
GMTK2EC: Extended Cab (as known as Double Cab) Chevrolet
GMTK2CC: Crew Cab Chevrolet

As so on...

http://imcdb.org/vehicles.php?make=Chevrolet&model=GMTK2XX&modelMatch=2&modelInclChassis=- on

I already used this Wikipedia page as source for Wikimedia Commons "jobs" (including for moving some of your pictures, rjluna2 ), but to be honest these codes are unsourced, for now. None of the references given in this WP page refers to anything else than to K2XX (when mentioning something about it...).
Shouldn't we wait a bit and/or find an official site giving these platform codes before using them?

It is your call, eLMeR

A couple days ago, I went to get my car to be serviced and able to snap these pictures for a good visual reference here.

2017 Chevrolet Silverado 1500 Regular Cab/Standard Box WT 2WD (Observe):


(Reverse):

Here is this year's Silverado Special Edition...

2017 Chevrolet Silverado 1500 4WD Crew Cab Short Bed High Country High Desert Package (Observe):


(Reverse):

This edition doesn't show much externally...

2017 Chevrolet Silverado 1500 2WD Double Cab Standard Box LT All Star Edition (Observe):


(Reverse):

Coming up with a brand new Chevrolet Silverado Special Edition:

http://www.msn.com/en-us/autos/news/chevrolet-reveals-centennial-special-edition-silverado-and-colorado/ar-AAsA5ea?li=BBmkt5R&ocid=spartandhp

Now it has own panel at: http://www.chevrolet.com/truck-life/silverado/special-editions#centennial

2017 Chevrolet Silverado 1500 4WD Double Cab/Standard Box LT Z71 Rally 2 Edition

(Observe):


Reverse:


You can see my own car likes to sneak up here

Here is this pickup truck that I snapped last fall:

2018 Chevrolet Silverado 1500 Custom 2WD Double Cab/Standard Box

Observe:


Reverse:


Apparently, my car wants an attention here

2018 Chevrolet Silverado 2500HD LT 4WD Crew Cab/Long Box

Observe:


Reverse: