From the moment we drove the rv off the lot there was a hurendous clunking under my feet and behind my seat. After spending a couple of hours under the coach I have finally cured it. I have seen on the forums a lot of people suffering this clunk at their feet and it was concluded in all of them as with mine it is the upper shock bolt. Although it is snugged up it is not torqued. It requires about 380 Ftlb of torque to set it. Mine was around 30-40, enough to make you think it is tight untill you drive it! Tightened it up and it is absolutely silent now.
My second issue was the rear mount for the leaf spring. The machining on it must have been off because when the shackle is installed and weight on the coach there was only .090 of clearance and when hitting a bump the rubber would compress and contact between the mount and shackle would make a clunk. I pulled the bolt on the lower link and moved the shackle out of the way and ground the bottom allowing more clearance and that clunk has also gone away now.