See picture below...
The vaccuum lines for the 4wd axle disconnect system always seem to get unhooked, melted, or ripped totally off. Here is a way to check to see if everything is hooked up right, and if it isn't, how to hook it up the right way.
On top of your transfer case will be four nozzles that control your front disconnect system for your 4wheel drive.
The red line coming from your transfer case is the hose for the vacuum source(constant). That will hook up to a hose running behind your air cleaner, if it is still there. Take a look and you will probably find the remains or the original red line. If you don’t have the remains of the original line that is hooked to the constant vaccuum source, find a port on your intake manifold that has a constant vaccuum(or ports on your carb).
Take apart the plastic housing around the vacuum harness(don't break it) to see the lines. Connect what seems to match up for now. Your best bet is to cough up the $30 that a new vacuum harness costs at the dealer and install that instead of driving yourself insane with broken lines.