2009 GMC 1500 4WD W/T pickup with tow package, bed liner, low mileage work truck

I bought this new and ordered it to my specs. Four wheel drive, eight foot bed with dealer installed rhinoliner, black exterior, titanium/black cloth interior, tow package (heavy duty radiator, alternator, battery, hitch receiver with wiring, oil coolers, etc), 5.3l v8 (the best half-ton engine there is,) upgraded factory tires on steel rims (which unlike aluminum don't leak). Full-size locking spare. The only change is I added a trailer brake controller (I towed a car with a low-boy exactly three times). It has custom made $400 Western-blanket-style seat covers on it since it was almost new.
NO power windows, locks or any of that junk that breaks anyway. Never turned the Onstar on but it's there. This is a mean-business working man's rig with all useful equipment and the mp3/CD player which was standard and plays music. AC still blows cold.
It has one large dent/paint scrape in the passenger cab corner / door is a bit dented there where I backed into a carriage corral, and a few minor gaffs to the tailgate, inside bed, and front pass. fender that are barely noticeable. I have dropped the price down a thousand bucks from FMV ($13,934 according to KBB.com) so you can fix these if you want. It has the usual truck clunks when backing up or whatever, but NEVER a single tranny slip or engine noise. Exhaust and undercarriage very solid. Still on 10-year GM rust-through warranty. No rust anyway.
I did all the maintenance myself: best oil filters, synthetic oil Mobil 1 or Valvoline, and front brakes were all she's needed so far. Probably time for rear brakes though it stops fine. Inspection stickers are out of date becasue I moved around for work a lot. There's a semi-recent highway hum which I'm assuming is a u-joint or bearing, from about 55-65mph (I drive 70, no problem).
All-in-all, great, reliable, decent fuel-mileage and powerful truck with the usual flaws and low miles (just turned 65000 which is well below average for 7 years). Drive this anywhere in the country. The last pic is to show the damage. The water you see on the tailgate is just dew running off--no problem with the paint.
I'm looking for a 1968-72 vintage c10 or c20 of comparable value, which is the only reason I'm selling. No other trades considered. Price is FIRM--ask all the questions you like, but I will not answer offers for less money. When I was looking at used trucks in '09, I couldn't touch a deal like this.