Massive Military Equipment Transport

"The third of seven Southbound Military Trains from Portland, Oregon headed to Yermo, CA through downtown Red Bluff on July 25th around 08:30. Equipment went in this order; 38+ Strykers, 2 cargo trucks towing arty, 33 humvee (hv) most w/ trailers, ambulance, 29+ Strykers,6 humvee's, 4 cargo trucks, 81+ humvee's w/ 3+ armored, 1 cargo truck towing fuel, 2 more humvee's. Anyone know what the boxes built onto some of the hv's are for?"