I am thinking of upgrading my 07 2500HD. We are buying a pretty heavy 5th wheel trailer soon, and think the 2500 isn't going to be enough. The hitch weight will be approx. 2800lbs, and the trailer will weigh in at 16,000lbs. I'm wanting a 3500HD. But have no idea as to what year of truck to purchase? New is out of the question. It's a really hard decision. As my 07 is in perfect condition with only 90,000 miles on it. Any recommendations would be appreciated.