On our '66, both sides were completely filled and hard packed- after cleaning, I had to repair rust, so when I made new pieces, I made a provision for water drainage- and some water does go into the front section of the rocker panel, but on the bottom of the factory seam, there is an opening for water drainage, and most all the cowl water dumps there. (there are openings down the length of the rocker panel also-make sure you don't seam seal those up or the rocker WILL fill with water). Best of luck to you. P.S. And yes, from all I've read, the top section of the vent DOES redirect the water, thus the reason for that "thick gum seal" around the perimeter of the vent housing. Also, if I remember correctly (it's been awhile), I had to fabricate some sort of baffle to replace the rotted one- that also re-directs the flow to the drain hole.
Last edited by gjones; 12-09-2012 at 04:37 PM.