Towing payload is 9600 or 9800 lbs. vs. 10K with the 6.0L. I think the 8.1 was 12K. No Quadrasteer with the 8.1 due to torque limitations of the rear end. (Which is actually the Dana front end off some 4x4 truck, I was told.)
There are people who have transferred QS to a Savannah van of similar vintage, so "portability" would make things interesting.
It is certifiably great for towing maneuvering. Low speed and highway. That ad wasn't kidding...
https://www.youtube.com/watch?v=Q0pbf4uNp3I
On the rust, I've got some new rocker panels for it, and a plan to re-engineer the inner rockers with something more structural, and tack the outer rockers on for 'looks', not structure. Things haven't sagged yet, so I'm hoping that addressing it this fall will work out. The new metal will be galvanized...