Be sure it actually has the tow package if you will need more than 7200lbs towing capacity. Check the rear diff sticker for the ratio. If it says 2.9something, it doesn't have the heavy tow package. You want 3.36 gears.
Beyond that, make sure you know history and condition, and check it out well. If it checks out, that's a good deal, but there may still be some room if you haven't haggled yet.
where's the Diff sticker located ...or is it a metal punch stamp on the side of the diff? I don't ever expect to need to tow anything more then a 12 foot trailer or 2 tons of camper
no oil leaks one owner and all maintenance records, not that I expect there to be many records with 34k on the odometer