I'd be a little skeptical of the Jag rear with 500 horse ahead of it if you abused it much. Yes they are stout, but they are just a middle level Dana and can be broken if you hit it hard and get the tires to hook up good.
The Dana is similar to the unit used in a lot of Corvettes and the guys drag racing those often replace it with a nine-inch Ford live axle.
If you are just driving the truck and not abusing the tires or towing I'm sure the Jag will last a long time.
