from NAC MK2 to KUB & B9TL
which other svs can get so good upgrading these days? 
No choice mah, because some buses have to replace the NAC Volvo
MK2s. Just happen that service 151 got direct Volvo MK2 to Scania
K230UB (while other services with Volvo MK2s got only Volvo MK3/MK4
fleets at most
). Anyway some
other examples:-
Service 3
majority Scania
N113CRB and Volvo MK3 fleets, now have Scania K230UBs
Service 6
NAC Scania
N113CRB to a new MAN demonstator (1 fleet only)
Service 37
full Scania
N113CRB NAC/AC fleets to full Volvo MK3/MK4/DD fleets
Some moderate upgradings like services 13, 24, 26, 53, 57, 130,
183, 185, 232, 238, 265, 268 which used to have only Merc 0405
fleets but now with new Scania K230UB fleets.