I believe it's because for HGDEP, they still have their Mk 4s on
Service 156 and 163 to sustain, whereas for AMDEP/BRBP, most (or
all) of the services that they are replacing are the ones with
almost full fleet of old Mercedes Benz O405 which is about to be
due for scrapping, hence the rationale for that kind of
deployment..
When will it be service 70's turn?? Though service 70 have majority
DDs but 8 of the fleets are still made up of those old Mercs
too.
But for HGDEP, is there a possibility that they will transfer
some MK4s over to BNDEP to replace those outgoing Scania N113 CRBs,
if BNDEP still not taking in Scania K230UBs? And also that HGDEP
have 22 Scania K230UBs currently SP and not assigned to any
services as perm yet 
