Sir, I commend you (I hope you still see this 4 years later). I don't usually create an account to reply to stuff, but this is exceptional.
My rear slider broke about a month after I got my brand new 2013 GMC Sierra 2500HD, and the dealer replaced it under warranty. I remember looking at the invoice which had the before-warranty cost (then zeroed out), and I remember gulping a little. Google search suggests that it would have run me at least $450.
I'm somewhat mechanically inclined so I found the Geniune OE part and ordered it and went looking for tips, and thus found your post. I followed your tips and the install went smoothly, in a very reasonable amount of time.
When the dealer's monkeys originally replaced the regulator in 2013, they failed to replace the plastic trim behind the seat. I found those pieces under the seat. But they also dropped a very nice 18mm impact swivel socket back there so I called it even. Eventually I gave up on the trium pieces and tossed them in the trash, because it was a minor cosmetic thing and I found I didn't care. As a result, I only had to remove the smaller seat on the passenger side, after removing the two 10mm bolts attaching it to the big seat, to expose the regulator. The dealer's monkeys had cut the insulator panel and folded it down to expose the regulator, so I didn't have to take that piece off either. So I guess their sloppy work saved me some time and effort today.
Anyway, my rear slider is now put back together and working proeprly, and I sprayed a bunch of silicone lube in the tracks and on the cable, to reduce tension and hopefully avoid a repeat.