I won't swear to it.....but suspect it is the breather tube for the axle. It is for when the water or mud or whatever get over the axle it won't get inside. It is not a "specialty" type of thing.....I would check Lowe's, Maynard's, Home Depot, maybe the local hardware store.....IMO auto stores/ parts shops may be much higher...could also check Pet stores aquarium shops....they may have a fitting to "lengthen" hose instead of replacing. Good Luck!!!