In a message dated 8/25/2013 6:08:36 P.M. Eastern Daylight Time,
ecaron1@COMCAST.NET writes:

I've  noticed for some time that my front grills seem to be a bit loose and
 rattly.  I realized recently that the lower grill is missing a screw in
the top center.  I think replacing that would be a good thing.  I  removed
one from the lower corner just to see how it would be in the center  place and
discovered that the screw just popped through

the lower rad  grille uses small plastic rectangular shaped  nutserts.
they are vanagon only...  im sure you could come up  with something
aftermarket though