Just got this truck in December. Replace a bunch of parts restoring it. Finally got it running like a sewing machine, but still can't get the front axle to lock into 4x4. I have pulled all the air line connections and cleared out the lines with air pressure, so I know they are clear. Lubed the switch at the trans and at the front axle. Pulled the front axle fork housing and checked the vacuum actuator diaphragm for any leaks. Lubed it. Put it back on. Have vacuum from manifold to the switch, but not getting any vacuum on either line to the front axle. Tried running vacuum strait to the axle from the manifold to alternating sides of the actuator and it won't move that way either. I am ready to put a cable on it now. What a rediculous idea to put all those vacuum lines to a 4x4 axle. What were they thinking?

Any ideas anybody?