Aw, you guys are no fun at all...
The gas tank is plastic and of course designed to survive high speed rear end inpacts, I can't imagine running it over a rock would be an issue, and anyway the Mo has such a short overhang in the rear that you would have to back into something REALLY steep to even try and hit it.
The Mo *does* have a locking diff...the center diff. Many SUVs have wide open front and center diffs and an LSD rear, but I would take a locking center over that every day.
No idea what the paint and tires have to do with anything...but as for the lack of 4-low and concerns about the tranny, well, don't go rock crawling or tackle the Rubicon Trail with this thing, but that should already be obvious.