factory looking hole in firewall???

[nikwho]

On my '83 there is a big hole (about 1.5" x 2") right next to the drivers side hood hinge that allows copious amounts of water to enter my cab when it rains or during a car wash. It looks like a hole cut by the factory and maybe i'm missing a cap or whatever should be plugging it. I covered it with duct tape last night because of the new carpet install but I would like to plug it with whatever is supposed to be there. Thanks, nik