Royce,
Unless you have your heart set on a gas engine HD, IMHO, 2500 HD trucks, towing, and diesel engines go hand in hand. Sure, a 2500 gas engine truck will tow your 8000 lb. trailer. But where are you towing? For me, for example, towing here in Colorado, with frequent trips into the mountains and over high mountain passes like Wolf Creek, Eisenhower Tunnel, Cottonwood Pass, Vail Pass, LaVeta Pass, Raton Pass, etc. etc. with a travel trailer dictated the Duramax diesel in my truck. Any of the current 2500 class trucks, whether GM, Ford, or Ram, will all do the job, it is simply a matter of personal preference.
I had a 2009 Ram 1500 that I used for a while to tow my travel trailer, but even the Hemi engine was straining at high RPM over the passes. A 2500 would have increased its towing weight capacity, but not the ability of the Hemi to carry the load.
Another consideration of diesel engines is the engine braking now available on all of them. Believe me, when towing a load downhill, this is a very valuable feature.
