The buyout of Conrail was approved by the STB in August of 1998, this permitted the creation of limited liability companies to accomodate equipment aquisition and other issues concerning the split. These were called the NYC for CSX and the PRR for NS, NS also aquired the CR reporting marks. Using these reporting marks for the companies aquired Conrail locomotives they began a renumbering at this time. This was prior to the June 1999 official date.
Similar in application that the PRR and NYC did in renumbering their locomotives prior to the official creation date of the Penn Central.