I don't think you would have any problems, they put a 5 speed behind the 4.8 and I don't think there is any difference between a 4.8 and a 5.3 or as far as that goes a 5.7 or 6.0. I know a guy in Michigan that has a new 04 model that had a 4.8/5 speed and he is putting a 6.0 and a T56 and hasn't had any problems.