I had the cowl off of my 89 the other day and noticed there was an access hole just below each wiper. Hmmm, wonder what the could be for? So I removed the plastic piece just under the fender/door, stuck a hose in the access hole and blasted some water in there. You wouldn't believe all the garbage that came shooting out of there. I would imagine that with all that crud in there it is a good place for water to collect and create rust. Just a piece of advice to prevent rust and it's easy to do.