I'd like to propose using this thread to solicit specific symptom descriptions of the various drivetrain problems that can occur -- searching the many forums, few have narrowed down exactly what each broken object sounds like or behaves. This would be very helpful as a central reference for future searches.

For example...

Driveshaft center support/bearing. What does it sound like when the rubber piece deteriorates? or the bearings go bad?

Viscous Coupler -- this has been mentioned as going bad frequently on AWDs, but specific symptoms are not described.

Freewheel

general "clunking" sounds -- what specifically is causing the clunk? What is hitting what?

etc.

 

The Torque Tube upper arm bushing, where the torque tube is bolted to the undercarriage, fails. Mine split/disappeared, enabling the clunks. Indy mechanic showed me the driveshaft/torque tube movement on the rack while his assistant shifted forward, reverse quickly. It rests on bolt head, then when torque increases, lifts up and bangs into the undercarriage. Rubber bushing prevents this banging. Cheap part, cheap labor.

Photo here...
http://carrepairphotos.shutterfly.com/pictures/9