When people want a luxury Ford pick-up, they tend to check the box for the King Ranch edition on the options list at the dealership. When people want a luxury Ram pick-up, they check the Laramie Limited option box. When people want a luxury Chevrolet pick-up, they... go to a different dealership?
To me, this doesn't make a whole lot of sense. With the other trucks, all you have to do is select a different range of options or trim, and there you go, you're set with a new, classy truck to go "do a hard days work" with. With Chevy, though, you're directed to a completely different place, known as your local GMC dealer. Sure, you could just completely option out your new Silverado, but what's the fun in that? You want to set yourself apart and let everyone know "I PAYED TOO MUCH FOR MY TRUCK!"... or do you? Why not just check an optional package box and have your leather covered, ass-warming seats? Some of you might say "well, look at Toyota/Lexus" or "Isn't that what Honda and Acura do?" and yes, yes it is exactly the same thing, fundamentally. But here's the difference. A Honda and an Acura don't look alike. Neither do Toyotas and Lexuses. So at least they're putting an effort into somewhat changing what the car is, at least to the average car buyer. But not the GMC/Chevy twins. They're those two kids that always wear the exact same outfit on the playground everyday, and until you get really close to them to look at which one has that weird birthmark on their neck, you'll almost never be able to distinguish the difference. Because thats really what Chevy and GMC do. Their idea of "changing" is slapping some badges on and maybe changing the taillights up, just to see who'll notice.
I'm not claiming to be a professional bean-counter and know all the finances behind all the car companies, or even GM for that matter, but I do know that it's got to cost a pretty penny to have completely separate dealerships and commercial spots packed full of the same stuff you can find wearing a gold bow tie. So why not just save that money and turn all of that into a nice "GMC package"? It seems way more practical to me, and that way they can pass at least some of that savings on to the customer, so they can spend it on gas later on.