Just fixed my dad's this past weekend. May be able to help. Is the front differential engaging? The easiest way to tell is to get into an area where the rear tires can actually spin. Hold the brakes lightly and cause the rear tires to move with the selector switch in 4HI. Have someone else look to see if the front drive shaft is turning. If it is, then the transfer case is in gear and the issue is that the front differential is not engaged. At the front diff shift actuator (mounted on the back side of the front axle) there is a vacuum connector. There are two lines in this connector, a blue one and a pink one. When in 4WD, the blue tube should have vacuum on it with the engine running. If it does indeed have vacuum on it, the problem is with your actuator (part that's connected to the axle). If there is no vacuum on the blue line, then the problem is most likely the small solenoid that supplies vacuum to it. That was the problem with my dad's. This solenoid is mounted on the firewall on the passenger side at the top. There are two of them. The outside solenoid makes the front differential lock (4WD) and the inside one makes the front differential unlock (2WD). Hope this helps.
Wednesday, December 29th, 2010 AT 8:48 PM