2002 Ford Explorer Sport Trac 4wd problem

Not sure where mangos came from however, the 08 post described the problem of severe banging/snapping when in 4 wheel drive. It’s fine in two wheel drive. Seems to pound all through the drive train.
Happens under all conditions. Was suspecting the transfer case but now am not sure.
First time here folks , please bear with me.
Any recommendations/ suggestions ?