This is the specimen I acquired from Doug Williams at the Portland National. It is purportedly one of the four specimens that "walked in" to the Hershey PA NIA National in 1974. They were documented in use on the Magnetic Telegraph circuit between Washington-Baltimore-Phila.-NY. Ken Willick has dug pieces of them on an NYC route between Rochester & Syracuse.
According to Ray Klingensmith there are only about 6 specimens that he is aware of.