Read this before building Disco death-trap !!
Disco_1:
I would STRONGLY urge you not to put a 2" body lift upon a 5" suspension lift. This will be 7" of total lift and will make your Disco a death trap. RTE will tell you the same thing when you call them. Overkill, and no utility to this set-up.
What size tires are you looking to run? Even with a 5" lift, you'll have to do some trimming of the DI fenders and rear quarter panels anyway. Trimming is almost always the way to go vs. body lift. I don't even think Steve would sell you a 5" suspension lift with a 2" body lift.
Regarding your question of what you'll need, besides driveshafts as was previously mentioned, you'll need lower gearing and heavy duty axles. Building up your Disco will cost some dough, which is why it's typically done in stages. But if you are going to put 35's + on, which you probably will with a 5" lift, your stock DI axles aren't up for the task. Great Basin Rovers is probably you best bet for HD axles, as well as the gears and lockers (if you are getting the locked up while the diff is apart). If you are looking to go extreme, you may also want to talk to Keith at Rover Tracks who specializes in super-heavy-duty axles including Toyota and Dana 60 swaps. With tires that big, you'll also want to upgrate your stock drag link & tie rod. Additionally, you'll need some aftermarket wheels with less back-spacing (more off-set) to run tires that large. And you'll need larger bump-stops which RTE will sell you along w/ the lift. You'll also want upgraded rear trailing arms (A-arms are part of an indep. suspension system) with the set-up you are describing, I would suggest RTEs heim-jointed, angled trailing arms. Also talk to RTE about front radius arms or you'll have articulation imbalance and binding. You will also need extended brake & ABS lines.
Finally, if you don't already have adequate armor, you'll need it with the direction your headed. You are going to want push your gear to the limit (unless you are building a show truck) which means a low-profile front bumper, rock sliders, and a rear bumper,,,all with solid recovery points and skid plates.