Some friends and I ran the Rubicon in 2003 in two Nissans, both had 32" tires (bald tires on the Xterra) and rear lockers. It took us 3 days but we made it through with no major damage other than a small dent and a broken tail light, but we had to be really careful and go very slowly. Overall it was a great experience.
If you do go in a mildly built 4runner I would strongly recommend going during the week so that you can go at a slower speed without blocking the bigger rigs.
Pictures at this link:
http://www.blankwhitepage.com/gallery/rubicon2003Huy
- Matt