hose axle

I have a hose hanging from the top rear axle (driver side) of my 98 Dodge Ram. Where does it connect to?(The hose has fuel written on it)

it's probably the vent for the dif. with it having "fuel" on it, I'd bet that someone has replaced the stock vent tube with some fuel line. the stock ones just attatch to the frame, and usuailly have a little breather cap on them to keep stuff form getting in. however, you do not want to just cap it off, the dif needs to be vented to prevent the axle seals from blowing out when the dif fluid heats up.