These are Military, a few months ago there were a few hundred of them on www.govliquidation.com
for auction. There were a few that had been rebuilt and in the military shipping containers. The military doesn't rebuild their own, if the engine is having issues they pull it out and put in another. Rebuilds are done by a government contractor. I you enter Detroit Diesel 8v92 on Ebay a few come up, some painted green some silver. The military one's are usually 475 hp and have jake brakes. The military is getting rid of a lot of old 80's 90's large prime movers that have the 8v92 as the power source so you will see many of these popping up for sale. Last year they had complete Jake brake kits for auction.