Marshall should check to see if the jack in his Jeep’s spare tire well is rolling around. My Jeep recently had the exact same clunking sound after coming to a stop. I traced the sound to the jack that is stored in the spare tire well under the mat in the storage area. In my Jeep there is a full service spare and a small, short and very heavy jack; both the tire and the jack are supposed to be fixed by a screw to a central bracket in the well. Apparently after the last time the spare was used, the tire and jack were not properly stored in the bracket and were therefore free to move around in the well. The jack would roll around every time I would come to a stop, and sometimes also it would move a bit on starting up again, just as Marshall described. I would recommend that he check that his spare tire and the jack are both securely fixed in place. Since I have properly secured the jack and tire in my Jeep, the clunking sound has disappeared.