If there's no obvious play in the links, and the struts are not leaking, I would go back to the sway bar bushings theory. I had this problem, drove me and the dealer nuts. I had a little play to slide the bar around but the rubber looked to be in good shape. That little bit of play, under high stresses with the wheels hitting bumps causes a loud thunk of the bar hitting the hard rubber.
Brian
99 SVT
