What is the other set hooked up to? I don't have any extra levers in the cab? I assumed the other two were used as some sort of return line for the backhoe. (Obviously) I have no clue. To the right of the seat are two levers in front of the draft levers. The outside one is for the top adjustment, and it appears the inside lever actually turns on the hydraulics for the top to work. If it is in one position, the top adjustment doesn't work, and in another position the top does work. I'm not quite sure why I need another lever just to turn the hydraulics on to go to the top valve.