We had the same problem with Erie Lackawanna Diner 741. Originally we thought it was the 747. The only current ID on the car was an untraceable Conrail MW number. We found the origial car number marked on the inside of the door of the electrical cabinet.

By the way, is there any source for original or replica Pullman lighting fixtures?

Erie Lackawanna Dining Car Preservation Society
tstuy@eldcps.org