DOD ships by rail frquently, there are many DODX six axle flats. BNSF frquently handles trains of mechanized equipment from Ft. Lewis on those cars. Much of their equipment is containerized and ships on regular pig flats. Sit around Yermo for awhile and you'll see whole trains or large cuts of DOD business; Port Chicago still moves a lot by rail and a little over a week ago we rolled through there and one of their US Army switchers was cruising along.

As for the age and condition, I would put money on the notion theat the cars are in good shape. Concord doesn't get enough precipitation to rot away boxcars, but the AAR establishes Interchange Rules and Standards of Inspection. I would have to look it up, but I'm pretty sure there is an age limit. Age limits can be renewed through rebuilding.

Bad track? Another matter left to railway experts. Is CC a recognized expert?

Boxcars make great storage for railway museums, and look good too. Think about all the seat frames, electric motors, window frames, air brake parts, etc. that many museums leave out in the elements because they have limited indoor storage.