It's the hydraulic fluid hose that exits the pump via this hose and is then transferred to the steel hose to the accumulators in the rear. The hose has dampers in it to absorb the vibrations of the pumping of the fluid. It is thought that the hose that I have is the wrong I.D., thus these dampers are causing the vibrations/ rattling/ whining. There are some prior threads about this very same situation. I just need some info about the hose, or someone who would like to part with one.