In 1893 at the Chicago World's Fair the B&O displayed a vertical boiler 0-8-0 identified as the Mud Digger "Buffalo". As stated above the Mud Diggers had horizontal boilers while the Crabs had vertical boilers. Was this an original locomotive, a reproduction or a wooden replica? https://www.google.com/books/edition/Ca ... frontcover

These were probably reproductions. The question now is whether these were operational or static (as stated before)

If I recall correctly, this was thoroughly discussed in the trade press, and later in some B&O people's memoirs. Most of them were replicas or non-operating mockups.

Maj. J. G. Pangborn of the B&O had wood replicas of ancient B&O engines built for the Fair. I'm sure this was one of them

The B&O Museum owns most of the surviving replicas.

Phil Mulligan