The front floor passenger side of my 83 300D got soaked in a rain storm the other day. I pulled out the battery (none too easy mind you) the tray is badly rotted as is the area under the tray near what I am guessing is some wiring running into the body. The drain was plugged, I cleared that. I ran a hose and started to wash down the damaged area and confirmed water is flowing freely from underneath the dash :-( I will need to fill plug and seal the rotted out areas under the battery tray. Any recommendations as to what I should use? Body filler? Squirt foam in a can? Globs of tubed silicone sealer? Any advise is most appreciated.