Cowl gasket question?? (pics)

I've got a new cowl gasket for my cuda but I'm not sure which way it needs to be fastened. There wasn't a gasket on the car when I bought it so I don't have anything to go by. When I put in place to snap in on I can flip it around and it will snap the other way also.

Which way does it need to mount? Fat edge towards the radiator or towards the back of the car?