There was a big deal a few years ago where the epa stopped all military surplus truck sales because none of the trucks were epa certified. I don't know what got worked out (gov't lawyers- fighting gov't lawyers-in front of a federal judge- all being paid by us- yes america!), but they started selling them about 6 months later again.
I would be interested to know if the new oshkosh trucks that use the c-18 have all the emissions equipment on them, or if they have their own version. i was at a base a while back loading some stuff up and they were changing the starter on one, but I didn't think to look.
Of the surplus ones, there's one by me for sale right now, but he's been sitting on it a long time. High 5th wheel height, expensive tires and drivetrain to keep up, horrible mileage. Just not a real useful rig for most guys.