Well gentlemen, after listening to my truck sound like something was going to rattle loose from the engine bay every time I towed or went on the highway (not to mention the typical marbles in a can during any and all other acceleration), I took it in for service again. The technician "didn't hear anything". Manager asked if I wanted to drive along with the tech, to which I replied "that won't matter, you can't fix it anyways". I then proceeded to give the service manager a piece of my mind explaining that I think GM has a major issue on their hands with the variable displacement V8s.
Long story short, I got rid of my engine rattle/tick. Ford dealer gave me a nice trade in. I'm sure there is a litany of issues with Fords as well, but an obnoxious, unfixable engine sound is not one of them. Good luck to all of you!