Helping a friend swap an engine, its all in ( this is our first swap ) all is in where we think it should go following owners manuals and service manuals along with HT but this hose we cannot find what goes connected to it. Its right below the battery and comes straight up for a connection there, as if it connects to something up top. Any help would be great.

 

Follow it down.... where does it go?
It almost looks like the drain hose.