The loud bang you here as far as I can fathom, it's the front diff that locked and if one wheel gets to much power the diff lock slips and that is the loud bang you here. The Quadra drive II system does not allow more than 25% power to one wheel and if it gets more than that, the diff lock let's go and slips. And that makes the loud "clack, clack!!!!" noise. That is how we understand it. At the end of this video clip when I reverse out of the water hole you will here the front diff lock let's go.
http://www.youtube.com/watch?v=WSk3dtKCX2E