Transport for London has confirmed that the Route 66 will be using double deck buses. Likely to be used is the DW's from the cast off's of route 38 and 242. But the Peak vehicle requirement will be reduced from 14 back to 11 buses because London Buses added extra workings onto route 66 because of the capacity of the single deck buses.
From their press release
http://www.londontransport.co.uk/info-for/media/press-releases/2014/august/route-66-switches-to-double-deckerFrom Saturday 30 August route 66 will convert from single to double deck buses.Route 66, which is operated by Arriva Kent Thameside, runs from Romford Station to Leytonstone via Romford Market, Chadwell Heath, Newbury Park Station, Gants Hill Station, Redbridge Station and Wanstead Station.On Saturday the route's 60 capacity single deck buses will be replaced by double deck buses that can carry 87 passengers.This improvement has been made by Transport for London (TfL) to ensure that all passengers throughout the route can benefit from higher capacity vehicles.
In particular the service is very busy in both directions around Newbury Park Station, where many passengers interchange with the Central line.The change allows the withdrawal of the limited supplementary single-deck journeys which were introduced last October as a temporary measure pending double-deck buses becoming available.John Barry, TfL's Head of Network Development for buses, said: `The number of passengers using route 66 on weekdays has grown by 15% since 2012. Converting this route to higher capacity double-deck buses responds to feedback from passengers and local councillors, with benefits to all passengers on route 66.`This service change is part of TfL's management and development of a network that comprises around 700 routes across Greater London operated by 7,600 buses at peak times, carrying more than 2.4 billion passengers every year. TfL keeps the network under regular review, working with the London boroughs and other partners to help ensure that services can respond to London's changing travel needs.
As you seen from London Vehicle Finder that Route 66 uses the Alexander ALX400 Volvo B7TL's from route 66 where it's usually used for Route 370. But when the DW's come along onto route 66, would we be able to see DW's on route 370? We may never know till route 66 converts to DW's.