Thanks for this useful info...I'm sure there are very less such instances....because even if a weekly,IR tries to allot a New No with each & every train. Thus we can see Old Train No like 6003(HWH MAS),8003(HWH YPR),8009(HWH CSTM),3144(Darjeeling Mail),5623(ERS GHY) etc remains unoccupied even after several years.