Washing truck today and noticed a hose dangling near left rear of truck. Looks like the clippy thing disconnected, but it doesn't seem to be causing any issues...yet. 
I followed the line and it's attached to the rear drive shaft. Anyone know what that is? Ended up clipping it to the bed frame underneath since i couldn't locate its original location. Someone be so kind to tell me where it should be attached? Thanks in advance!

I followed the line and it's attached to the rear drive shaft. Anyone know what that is? Ended up clipping it to the bed frame underneath since i couldn't locate its original location. Someone be so kind to tell me where it should be attached? Thanks in advance!