Brian, Couplers were mounted on the car frame while frame was upside down. Only knuckles need to be installed.
The brake wheel will be installed.
Deck planks may need painting or wood treatment.
Trucks. The B&SR marked trucks from box car 57 will go under B&SR flat car 34.
At some point in time the B&SR marked trucks under museum built flat car 126 will go under Box car 57. Car 126 when built by museum, was built with bigger size timbers than car 119. Museum wants to build a new pair of heavy duty trucks for flat car 126.