I'm with you google
http://www.google.com/search?hl=en&rls=com.microsoft%3A*%3AIE-SearchBox&rlz=1I7GFRD&q=500+lb+explosion+mrap+&btnG=Search
the presentation is all over the net, the exact size of the bomb is the part that is the part that is not verified, if it ever was. IMo it could have been larger than 500lb, I would like to see the math on how much force it would take the knock an engine block that size off its mounts and move it 100 yards.
There is no doubt that the occupants will have ringing ears for awhile as well.