gas line confusion

hey guys i took out my gas tank to extend the lines so i could put it in the bed of the truck well now i dont know what line is what its a 92 dodge dakota with a 318 from what i can tell there is one out line one return line and a vent line tried swithing them around but couldnt get the truck to fire please help

is one larger than the other?

looks like two are the same size and the third one is smaller