The holes for the radio wheel (which is missing) and the bell, look like the are drilled afterwards.
One theory i have is that it could be a MPC 634, the original shell got damaged, and the exact replacement shell couldn't be found so they took a prewar 634 shell, drilled the holes and transferred the wheel and bell over from the old shell.
It is just a theory, but if other details indicate the train is indeed from the early days, this could be a MPC 634 engine. I don't want to claim that, though, if i am not sure about it.
You can see in this pic these holes don't look original.
