the rolling mine exploder
For a really good write up on what it is, and links to more pictures in the comments section, look at http://blog.hemmings.com/index.php/2008/03/06/march-military-campaign-now-thats-what-i-call-ground-clearance/
Good blog I read frequently, they do more homework on things than I do... I'm just happy to find cool stuff and show it, and give you links where you can read more about the thing.
Just for the record, I don't remember where I found these pictures that I posted 2 days before Hemmings, but this is a fricking cool machine, and Hemmings should get credit for great research.
For a picture of the back of this, showing the 3rd wheel, and ruining the 2 track awesomeness of how it appears here.