American Bell Pony Receiver: US567 and " FOR US GOV'T USE ONLY"

[allnumbedup]

I came by this pony receiver loose in a box lot. I remember a link for a similarly marked transmitter:
US GOV'T Transmitter

but can't find information about this receiver. It was among military headsets and tramsitters some of which could be WWIera.  This has a nice dark brown with the top and cap marked as shown plus a "Z" on top next to the terminal across from the serial number side.

[rdelius]

Most likely to identify that it is  not Bell property .Have seen older telephone parts with  similar markings