Lost all gears even 4X4 will not engage

Driving and stop sign so coming from a stop.I step on gas and I am going halfway through intersection lost gears like I popped it in neutral, and I coasted to a stop. First thing I thought was linkage and no works great. Then I thought because I heard no pop or anything that I lost a vacuum lime and so I look around down there and there is a elbow for a hose down there exposed, and it is on the transfer case. Where does that hook up to? Then I get towed home. I am hoping that is the problem, if not I am going to be using this site all night.