Mine does the same thing except it doesn't really seem to matter what speed I am going or where I have my wheels pointed. Over the past few months I have replaced: steering box, draglink, tie rod, all tierod ends, all four balljoints, shocks, wheel bearings, both motor mounts, tranny mount and torque arm, brake calipers, pads, and rotors. Pretty much rebuilt the entire front end of my Jeep and then some. I didn't do all of this because of the noise but I figured one of those things listed would take care of it. Also I don't have a sway bar or track bars, I use those to keep the tarp from blowing off of my stingray project lol. It almost sounds like someone is picking the motor up about 3 to 4 inches and dropping it. The only thing I can think of is the springs/shackles because they are the only thing that I haven't replaced. I have noticed that my spring packs shift around quite a bit after taking the track bars off. The drivers side military wrap is touching the mount on the frame and I can hear them cracking and popping when I am wheeling it. I am about to do a springover and will be replacing the springs and shackles (3.5" bds springs and 1" shackles) with stock length boomerangs and RE 1.5" springover springs. So we'll see if the clunk will go away.