To call the J-4 Class Mikados tired would be to do them a disservice. They were all rebuilt with new boilers, feed water heaters and trailing truck boosters, making them pretty modern engines. I am sure they had time left on their boiler certs too, so there would be no need for heavy class repairs for a while. Roads like the TA&G certainly would have viewed these as bargains on the second-hand market since they were still setup to operate and maintain steam in 1949.
Eric Reinert