Here are a couple shots of the innards. This thing does have a Signal Corps acceptance stamp on one side.

I thought it might be for a PE-237 – no luck. Wiring base is 6-pin tube like:

P1 NC to reed ( unenergized )

P2 gnd

P3 coil

P4 vibrator moving arm ( reed )

P5 Not used

P6 NO to reed ( unenergized )

thanks! – Hue Miller