Under Hood Jump Box: How Does This Work?

[AJC]

I have what I presume is a jump box, that is under the hood of my 84 wrecker. I'm having trouble finding info about how it works; since it must serve a purpose vs just running quick connect jumper cables.



I need to draw a wiring diagram to help figure it out. It has two 12 volt batteries in series going to one solenoid and a 6 volt battery going to a solenoid on the other side. The 6 volt battery is kind of throwing me for a loop. Hopefully someone has seen one before to clue me in on how they work. Thanks