I bought some ARC-5 and SCR-274-N parts and with it came a totally rebuild BC-456-E modulator. Perhaps it was converted to an intercom and/or audio amplifier.
It contains two VR150 voltage stabilizers and one 12J5 triode and three relays. The conversion was done to a higher standard than the average amateur will work.
All original plugs on the chassis are rewired so I assume it was intended to be used in combination with the ARC-5 or SCR-274-N installation.
Does it ring a bell the someone?
Nico - PA3ESA