I got rid of my droning by putting two small plastic clips as  buffers
between the rack and the body in the middle of the the rack above the
rearview mirror. After installing the Bus Boy seal the droning occurred only
at high speeds or high head winds. Now it's gone.
Hermann the German
"87 GL Westy 2.0lEurospec and happy with it"

P.S. Check out http.www.phenomedia.de for the latest rave in Germany. It is
a free computergame called "Moorhuhn". From what my brother in Germany told
me everybody there is going nuts over it.