ktmrfs wrote:
1) trim and cosmetics. Other than that, they are the same vehicle. there are some differences, GMC doesn't have the WT (very base version) and until recently Chevy didn't have the Denali equal, now they have the High country. but for other versions you'll find prices virtually identical.
2) I had an 04, Chevy after 125K miles went to our son and we now have a 2015 GMC Denali. We love both, and 04 was and is still trouble free. 15 only has 20K miles on it, but so far is flawless. very quite, better handling than the 04
3) I think the chassis changed in 11 and then it was updated significantly again in 15
4) as for towing 9K lbs, piece of cake, but expect between 10 and 13 mpg depending on (a) SPEED and (b) terrain. 60 or so on flat ground I can get 13, usually it is in the 11-12 range.
LOL, is this what the salesman told you? Same chassis since '11' new body style for the HD's in '15'