Didn't the 3.5s come with a 4 speed auto while the 4.5s came with a 3 speed? That's all auto talk of course, but I am sure that if there is a big piece of tin on top and not the beautiful intake runners, you haven't found a 6.3 liter diamond.

Both the 3.5 and 4.5 look virtually the same under the hood with the big air cleaner on top of the motor.