That may be a vacuum line that connects to the solenoid, I'm struggling to tell from the pic. I'm pretty sure the vent line for the hubs is curved 180 degrees and then just ends, it doesn't have a connector at the end. The vent tube also ends much closer to the upper strut mount. Hard to tell from the pic, but I think that connector goes to the vacuum tree that supplies vacuum to the IWE solenoid, IWE hubs and HVAC. There's also a vacuum reservoir behind the battery.
This thread has a good pic from SafariGoneWrong of the vacuum lines in that area and a diagram of the 4WD vacuum setup.
Does anyone have a photo of their vacuum hoses that are installed correctly. Mine got messed up replacing the AC and I’m afraid I won’t connect it correctly. I have a 2003 EB Expedition 5.4 :) Please help :)
www.expeditionforum.com