if I am not wrong the LA allocation last time is:
16XX series -- Western based
68XX and 56XX series -- Central (TPY, AMK etc) based
49XX series -- Eastern based
But at around 1992 when 198 swapped its LO2x with 157's LA, some of
the 157's BRBP LAs (Like SBS5602G, SBS5604B, SBS6888S etc) were
being transferred to BBDEP.......