NTSB report does strongly suggest that the #1 MRAPV (mine Resistant Ambush Protected Vehicle) broke loose from its tie-downs during the takeoff sequence and smacked into the aft pressure bulkhead
I had an off the record discussion with an FAA type a while back where he said that not only had an MRAP broken loose, it had punched a hole in the airplane and they had found bits of airplane and cargo on the runway near the takeoff point
