Use the experience of other users. A few years ago I seen a good friend of mine at a truck dealership, trying to trade trucks. He pulled a decent size TT with and old 390 ci ford - the salesman about convinced him the new 6 cyc would do as much as the 390 ci. I was selling a 5th wheel a man bought it but had no truck, he came back later with a small ranger and small engine, the dealer has assured him it would do the job, I refused to go thru with deal telling the man no way would it work. He left went back and bought a real truck.