Dually rearend question
 

This one is for the dually owners, I took the bed off when I painted it and now that it is back on, there is a rubber vent hose hanging down from the bed bottom, so I figure it must hook up to the rearend, to vent it, well I cannot for the life of me find where it goes. Does the dually rearend have a vent opening? Or does this hose go somewhere else?