Ok so all you would have to do is buy a leveling kit? or just get the normal suspension lift kit for the rear?
Sorry if this sounds repetitive but i was thinking about putting a Cummins in place for my 318 on a 99 1500. so i just wanted to see if the stiffer 2500 springs would work all the way around so there would be less sag and make it handle good without bottoming out the 1500 shocks/springs, and what ever else would happen with the heavier diesel is put in.

 

I've got 2500 springs in the front & 3" blocks in the back.
Stiff is not the word,.. Buck/Board is more like it!
Got them for my plow,.. Great for that,.. Horrible ride though.