1982 W150 4WD won't engage

[likes2build]

Bear with me on this one. I'm 500 miles away from being hands on and it's my sons truck and 4wd is not in my education. He has a 1982 W150, standard trans, 4wd, lives in New Mexico and is stuck in the mud at his house. He manually locked the hubs and shifted the transfer case to 4wd, the indicator light goes on for a few seconds and shuts off. He said he's stuck pretty good and only the rear wheel spins.

Any suggestions on where to start looking? Thanks

 

[crazzywolfie]

almost sounds like broken vacuum lines or maybe a sticky or stuck vacuum actuator if it has the auto 4x4. could also be worn out hubs. if they can see the front drive shaft spinning it will at least help figure out if the issue is in the transfer case or front axle