UBL was part of SCR before SWR was formed. Hence UBL retained 73XX - 7 for SCR and 3 for UBL for express while 27XX - 2 for SF and 7 for SCR for SF trains. The only exception being Swarna Jayanti Exp. I don't know how it got 27XX while MYS was part of SR before SWR and SR had 26XX.