Any of the big 3 3/4+ ton diesels will do well with that TT. If there is a 5er in your future, get a 1-ton SRW for the minimal upgrade cost. You can also check out Ford's HD payload package F-150. 4x4 crew cabs with 2100 pounds of payload, extended cabs with 2400+ pounds. It comes with Ford's Ecoboost 3.5L which does well at altitude, plenty of power, and better unloaded ride than the 3/4+ ton trucks.