@BJ Oh, one final comment. Common "internet" wisdom is that the automatic transmissions on these are garbage. That's hogwash. The people complaining, when you really look into it, are the ones overloading them/towing too much weight, never changing the fluid and filter, and then complaining when the transmissions blow up at 180k miles. If the fluid and filter is changed even at double the maintenance interval, or the truck hasn't had it's absolute balls beaten off of it, the transmissions are totally fine.
If you're worried, I forget the exact changeover year, but later trucks like my '06 have a slightly stronger 4L-65E.