those jacks came with the cover plate and the four wires with spade terminals . nothing was connected to the block which is a separate piece. Its not like a jack you get today where it comes with the wires under the screws .The concept was you could attach the cover plate to a existing 42a block in a hardwired situation and turn it modular
so cutting off the unused wires wasn't uncommon , cutting them was quicker than putting them under the screws
I don't understand the Union reference either
