Why are some trucks black and some silver?[%-)]
I think they had silver if they were used for passenger service, and black ones if for freight; but I’m not 100% sure about that.
I know all the BSB engines had black trucks.
That would have been my guess too but I thought I have seen black trucks and silver ones on the Empire Bldr. in photos.
This would be a good question to post on the Great Northern (gngoat) Yahoo group page. There are many very knowlegeable folks in that group.
Roger Johnson