According to wiki (I know, I know, but it seems as if the freighters have all the really late line numbers too) the pure freighter B727-200F was only launched in 1981, only a few years before 727 production stopped altogether (and looking at the database, only for FedEx.) I'm curious as to why Boeing didn't make a freighter out of the 727-200 earlier. Was the cargo need fulfilled by the -100C? Or was there just no demand for a freighter around that size at the time? Or some other reason altogether?