Just with reference to buss14's post on the main page for GNE,  I think that although I love the B9TL, they're a wasted bus on the Cobalt Clipper as none of the routes need such power and it is a lot of fuel to use for not too demanding work. At the end of the day, if Volvo B5LH can cope on the 308 albeit a tight timetable courtesy of Arriva, then I think the Streetdeck could cope alright with the 309 / 310 / X39 with no issues.

I personally think that if the Streetdeck was to use less fuel than a GKN modded B9TL, bearing in mind that only one of the Cobalt B9s (I think) have already been done, then I've got a sneaky feeling that GNE could order Streetdecks for the Cobalt Clipper and put the B9's to good use elsewhere like this depending upon what changes happen to the West Durham Express services. The Fab 56 could also go back upto every 10 minutes too:

6085 to 6098 = 14x GKN B9TL / Deptford / Fab 56
6099 to 6100 = 2x B9TL / Deptford / Spare
6101(T) = B9TL / Riverside (or Hexham) / Spare
6102 = B9TL / Riverside (or Hexham) / TEN
6103 to 6104 = 2x GKN B9TL / Deptford / Fab 56
6105 to 6111 = 7x B9TL / Crook / Pronto
6112 to 6117 = 6x B9TL / Stanley / West Durham
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Further Cascades and allocations:

6084(T) = B9TL / Riverside (or Hexham) / Spare
3941 (T) = B7TL / Riverside (or Hexham) / Spare
3942 (T) = B7TL / Crook / Spare
3963 (T) = B7TL / Stanley / Spare
3964 (T) = B7TL / CLS / Angel Spare

3962 and 3965 already part of the Angel PVR.