I was also trying to find out the difference between these 2 double ended studs for the heat shield between 6509863AA and 6510141AA. The are both double ended studs for the heat shield. What locations do each of those part numbers belong? They are almost exactly the same length. I can`t imagine the length would even matter? I did notice that the nut portion of the stud looks more rounded off than the other one which has more sharp edges to the nut.