Suspension or body lift, the lowest point of the truck is still the bottom of the diffs, the only way that changes is tire size. A suspension lift isn't going to gain you ground clearance.
Yes, may gain on breakover, approach and departure angles, but, not a whole pile of alot. But, I'm the kind of guy that stuff 35's on a truck with no lift, and 44's on with only 8...
On these IDI trucks, a body lift does serve a practical purpose of making room for turbos etc, and making maintenance in general a whole lot easier...
Same goes for my 460 truck, on the long wekeend I did the clutch in it, on the side of the trail, in just under 2 hours(had to yank the pressure plate and clean the mud of of it)