YA172 is a set of 25' jumper cables made to plug into a bumper mounted socket.
They were made so you didn't have to open the hood for jump starts on wreckers, etc.
There were 5' cables from the truck battery to the rectangular (male) bumper socket plug.
The jumper cables had a rectangular (female) plug on the end that just plugged into the socket on the bumper.
It looks like you may have mounting brackets and socket covers.