Here's a list of the Boston cars that I know the conditions of:
5821: currently can limp along well enough to do a photo runby through the loop. If the damaged motor is repaired in time, then it should be operable
various Type 3 plows: some operable (including 5106), some not
3424: not operable, needs poles and an inspection
#4 EBT cars: should be operable if poles are installed
396: does anyone know if this still runs? If not, it should at least be pulled out of Riverside for display
PCCs: none are operable, but one or two look presentable enough to be pulled out for display
3283: IIRC the controllers are shot and it's been removed from operation
To my knowledge, none of the other Boston cars at Seashore are operable, though I could be wrong.
"The destination of this train is [BEEP BEEP]" -announcement on an Ashmont train.