Dart gas cap confusion

I bought the grey cap , was advertised to fit my 70 Dart, NO GO.
As you can see the attaching points are deeper in the filler neck with the orange cap.
The orange cap will allow air in but not out. I have a CA car with the 4 nipples on the gas tank that go to a fume capturer, which I will be removin. Should I drill the orange cap so that it can have air coming in and out ??

BTW, WHAT YR(S) DOES THE GREY CAP FIT ?

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