Fuel system questions

[74 340 4speed]

I was working on the 'Cuda today, and I got a new fuel line and fuel pump installed.  I took out the gas tank and it has four vent hoses going to a small box that a return line goes to.  What is this small box with the 4 outlet lines?  Do I need to keep this on the car even though the return line isn't being used? (I have a holley carb)  Are these vent boxes reproduced?  Mine is pretty rusty and nasty looking. 

[Chryco Psycho]

the "box" traps fumes , it could be removed but you have to have a vent on the tank or it will create a vacuum & stop fuel flow , in 70 there was a line run over 1 ' higher then the tank into the trunk & back out into the frame rail you could do something similar for yours
 I have never seen a repro vent trap