loss of vacuum line on 1994 Dodge Ram 2500

there is a 1/2 inch vacuum hose at the rear of the intake manifold next to the brake vacuum connection and it runs the 4-wheel drive motor on the front axle. Where does the other end of the hose hook to?

Asked by for the 1994 Dodge Ram 2500
The hose either routes to the Vacuum Reservoir or the Transfer case Vacuum Switch