As I remember, there isn't much to be seen under the grille.

If you take the blower cover off, and remove the blower motor you will see the tubes that eventually drain all the water off the windshield. They are probably plugged which will allow water into the cabin. If any of the various corners in the plenum have rusted through, that will also allow water to get in.

I did a post on this last year.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe