97 4x4 front axle vacuum line
 

I've got a 97 4x4 5.4 that the 4x4 switch and indicator lights show 4x4 engaged. however I've got no front wheel action. went looking and found the front axle vacuum line disconnected at the top. I went looking for the home for this line in the engine compartment and couldn't find any.

Could someone tell me where the top of the line goes? TIA.

Been a while since we had our '97, so don't take this as gospel-
I think there's a vacuum reservoir on the passenger-side that the hose plugs into.

The hose looks like it goes in that direction, but is it on the firewall, under the battery, or behind something? I didn't see a reservoir that jumped out at me.

Thanks