I suspect you are correct in that it is an old transient supression
device. I don't know what you would use it for in amateur radio, but you
might try to contact Fisher Custom communications. They are in Torrance,
California, USA.

Contact Info on the site at: http://www.fischercc.com/transframe.html

Ed K7AAT

Thank you Ed, i'll try to contact them !

Ciao,
73 de Riccardo IK5WQO