I know you said you don't want a dually...however, you might want to rethink that. The real life pin weight on the 3670 is pushing 4,000lbs, and your gross trailer weight is 16,000, not the 14,000 others are referring to. That type of weight is going to max out and probably exceed most rear axle GWR, not to mention the gross weight rating of the truck itself! You really don't want to put that much weight on just two tires either.
Any of the big three can easily tow that unit as far as engine strength, etc., it's of more concern as to what weight you subject your axles, tires and suspension to. And remember, the 4x4 also takes away from your towing capabilities...you don't want to end up with less truck than you really need. Not to mention, the dually provides you with extra braking capability and more tread surface on the ground for better stopping power. I would not tow that size trailer with less than a 1 ton dually, ever, JMHO!