the "clunk" is not unique to VX's, it happens in 2gen rodeos and amigos/RS's too. My thoughts on this are the slip joint in the rear drive shaft. When you stop hard, the front end squats more and extends the shaft. As the rear end settles, the truck will either clunk then, or on takeoff. Mine thumps/clunks on takeoff, just as i take the slack out of the drivetrain. Not sure if this is it, but it gets better after i lube up the shaft. (8 bolts and some grease)