How do I know for sure the four wheel drive is working?
 

I just got an 87 silverado 4x4. Its an automatic with manual hubs. When you turn the hubs from free theirs a kind of click as they come out free wheel but not one as they go into the locked position. Should they? I lock them, shift into neutral than shift the transfer case into 4h or 4l but it doesn't seem like the front wheels are getting any power.

Go to a large parking lot. Lock the hubs in and put it in 4H. Try to make a sharp left or right turn - slowly. If it is very difficult to do and the front end skids as you turn - it is in 4 wheel drive. Do this for testing purposes only and for a short period of time...