I took your advise and tried that . With 4wd engaged I can't turn front drive shaft or wheel . It's def engaging, I don't understand the crazy part that it does this noise wether the car is moving or stationary when it's in 4wd and reverse . Forward is fine , just reverse and it has to be 4wd . I'm completely baffled. I would say transmission but it's only when front axle is engaged .
I am sorry, I missed a big part of the diagnosis above..
When the truck in 4wd, and all 4 wheels in the AIR (on jack stands!), truck in park, then try turning the driveshaft. It should not turn. Then try turning the CV axles, the wheel on the other side should spin in the reverse direction. now put the drivers side front wheel on the ground, try again, turn the steering wheel full turn one direction, try again, turn the steering wheel full turn the other direction, try again. Now put the drivers side wheel in the air, put the passengers side wheel on the ground, and repeat the instructions above.
Edit: I guess the rear axle does not have to be in the air, but the front needs to be as outlined above