Motor and axle questions are difficult to answer. The tire size is what really determines both. Running 32's your fine. 35's is when you start wanting heavier axles and more power. Regearing helps significantly with power. 54's well now your talking...500+hp and 1 Ton axles or Rocks.
So what is your plan on tire size?
License to kill gophers by the government of the United Nations. Man, free to kill gophers at will. To kill, you must know your enemy, and in this case my enemy is a varmint. And a varmint will never quit - ever. They're like the Viet Cong - Varmint Cong. So you have to fall back on superior intelligence and superior firepower. And that's all she wrote.