I have a 2001 Durango with 4X4 that was making some ungodly noise the other day when I went to put in 4X4. The noise was instantly apparent with the switch over. I bought a new hub had it installed by a firend and the noise was the same. If I have the drivers window down and come to a slow slow stop I hear alot of clicking like "marbles". As soon as I take it out of 4X4 the noise stops. It is only on the drivers side. Any thoughts?

 

Get under the D and check for any play. Also check the oil level in your front diff.

 

Your cv axel sounds like it's done. The boot probably got cracked and leaked out all the grease inside. When it slips that will give you a jackhammer or an impact wrench sound. It also might be the front diff., but I don't think so unless there's a lot of play in it like Green mentioned.