Trunk Leaks Water At Fuel Filler Area

I just bought a 94 GT and found water in the trunk after a rain storm. I took all the trunk panels out, then I put the rear seats down and crawled into the trunk with a flashlight. I had the wife put water all over the car. I found water pouring in from the area where you put the fuel nozzel in. It was leaking between the the quarter panel and the plastic box that holds the filler neck to the quarter panel. I hope this makes sence. I'm guessing there is a gasket between the quarterpanel and the plastic box but I don't know what to ask for.

Has anyone changed this gasket or had this problem?

did a search but couldn't find any info on this problem.

Thanks for the reply Toyman. I will check the drain opening.

When I search "filler neck gasket" I just get info on the filler neck to tank grommet that everybody seems to need replaced.....I'll probably have to do it soon too I guess.