2003 E250, bone stock 2wd with open rear diff. ~8,000lbs loaded. 265/75/r16 general grabber AT2s.
I have had my mind blown as to how many places I've been able to get without getting stuck without even so much as a LSD in the rear. Snow seems to be the most consistent limitation, however. This was ~ 3 miles up a forest service road outside of Moab, this past December. The entire road had ~8" of fresh snow from the night before, hadn't been plowed yet. It was steeper and the snow was deeper than the photo makes it look. Knew I was pushing my luck and finally slid off of the road and in to a gulley on the side. Best/worst part was trying to dig ourselves out against the snow bank. Ended up getting pulled backwards enough by a Nissan Titan 4x4. While we were shoveling, a subaru and a toyota tacoma 4x4 got stuck going around the same corner.