2014 e250 don’t know what this is
 

this hose is connected to axle and has V connector on other end with nothing else attached to second side of V connector. I think differential fluid is leaking from V connector. What is this hose and what other hose is missing?
https://cimg2.ibsrv.net/gimg/www.for...7cabfb0fe.jpeg
Black(wet) hose in question
https://cimg3.ibsrv.net/gimg/www.for...65eb67203.jpeg
V connector
https://cimg4.ibsrv.net/gimg/www.for...9932f0674.jpeg
V connector
https://cimg6.ibsrv.net/gimg/www.for...d8d8e8ecc.jpeg
Axle connection

It's the axles vent tube.
It should be open on the fitting end, and remain in its position well above the axle. The angled fitting in a downward position and aimed towards the rear of the van. Generally you don't see any lube residue. Might check the lube level. Has anyone service the axle?

Thank you for information. I will make sure the vent is facing rear. So it is unusual that fluid would be coming out, don’t know last time serviced I’ve only owned 2 years. I will get it serviced.

Rear gear oil 2014 e250 Dana 60 axle
 

My ford dealer said ford changed using 75w90 to 75w140 but when I look to buy oil 90 weight appears to NOT be synthetic whereas 140 is. I am assuming no one has ever serviced this as I got van at 74000 miles so pretty sure it’s original gear oil. Current mileage is 82000. Is it ok to pump out old and put synthetic in. My differential has perfect seal and I don’t want to mess with that. Advice? Also know I need LS-3 for it too