Having a slight problem with the transfer case not fully engadging on my 1991.Put in 4x4 and it makes a clicking sound when turning right or left. please help,pulled the solinoid and it moves in and out when powered up .What else could be the problem

The hubs, Do you have manual hubs?

No manual hubs

Check the auto hubs. Sounds like a hub isn't engaging.

On dry ground/pavement, engage 4hi, start moving about 5 MPH and turn the wheel full left and right, if the vehicle jumps while turning left or right, then 4hi is working.

As far as clicking, not sure where that would come from. If his front drive train is like my 2000 blazer, then he wont have locking hubs, they are full active hubs just like a front wheel drive car.

I don't here the clicking until I turn left or right with 4x4 engadged.driving in a staight line no clicking

If I recall, that may be normal if your driving on dry surfaces with 4hi engaged. Have you tried 4Lo to see what happens?

front on 4wd gm is a static mounted diff with two front axle shafts like a front wheel drive car.

if it only does it when turning then its probably the axle shafts, they dont last very long. the older ones usually dry-rot the cv boots and let the grease out. thats were i would start looking, and grab ahold of it and see what kind of movement you have.