What driveshafts? Personally id be looking at a 1350 with that much power, probably not needed and may move the weak point though..Just a thought.

 

I would stay with 1310's that way the shaft ujoint will be the fuse. A lot easier to fix that than axle joints or ring and pinion.

 

Fyi the iron block is 101lbs more than aluminum block. My dad had a hd 6.0 with a allison trans. Got a whooping 13 mpg that's why he sold it and got grand Cherokee.

 

That is a bit more weight to consider, paticularly in additon to my heavy powerplant winch and heavy front bumper. I will probably be (I think) losing one of my two diehard platinum batteries with the swap, so that is at least 40lbs. trimmed off. I believe this is the same engine in my wife's 2001 Denali, good power even for that heavy vehicle. We get a little over 13mpg city and a little over 17mpg highway with 170K miles, but I would think in the smaller 4 door jeep the mpg would be a bit better. Not my daily driver, so mpg is not my priority, but it is good to consider. I think I was only getting around 14mpg on a good day with the stock engine and 37s.

I have 1310 wood's driveshafts, and those are a easy to replace weak point, should be still covered under their own lifetime warranty if I break em.

 

I think the Denalis got the aluminum block