4008 is at Yukon. Spotted this morning in Bay Ridge on the S79 still with CAS stickers. 4010 I'm assuming is at Yukon too because it was on the S44/S94 and I discovered it using Bustime. It looks like Castleton might send their remaining NG's to Yukon.
I would think they would have been transferred to Yukon because I have not seen them on the X10 or X14. Probably some of the stickers have not yet changed.
From my knowledge and sightings and as other members have said, these are the local bus transfers to Charleston: 6191, 6193-6197, 6199-6208, 6210-6230, 6232-6236, 6241-6244, 6248, 6252-6253, 6258, 6261, 6271-6277.