Loud popping sound when I'm in 4WD??

[Crossfit Jeep]

I should clarify this happens when I'm turn and moving forward. The truck drives fine, but every time I put my truck in 4WD and not all the time, but often I will hear a loud popping sound.

What is this or could this be?

 

[Grady]

Are your lockers on when this happens?

 

[Pro Drywall]

I would have your drivetrain looked at, something doesn't sound right.