The Ford filler tube has a somewhat complex set of breather connections. One is a condensation trap that is connected to the top of the tank via a very small tube. another is the breather hose which has a ball valve that shuts off the connection if the car is rolled over in an accident and the third 12mm connection is to allow air out of the tank when filling up. Well I think that's the theory? The hoses will be sealed where they enter the bodywork once I'm happy it is finalised.