I wonder which carriage will be going then?
I guess if they keep the 2 with toilets it's the one with motors that would be going. Which I think would be similar to the original 458/0
The BZ vehicle which is the ex-460 vehicle will be going. The intermediate vehicle with the universal access toilet is a motored vehicle. 741xx also known as the BL vehicle.
458/5
current formation is BJ-BZx-BK-BL-BM for 8501-30
8531-8536 is AAx-AC-AF-AG-AHx the Codes are different as the 460 code was retained. The AB, AD, AE and remaining AC, AF and AG vehicles became BZB, BZC etc. With the last letter a clue of its 460 origin.
the driving vehicles got messier as 8531,8533,8534 and 8535 have the eight original AA cars so they have a AA and a AHA. 8532 and 8536 have AH (luggage vans), so they are AAH and AH.
getting shot of the 460 vehicles will make life a lot easier.
so the formation will be for the retained units BJ-BK-BL-BM
(one assumes 334 are CN-CO-CP)