If it is a 69/70, it would have a pcv system, I don't see that and like you said already, no oil fill so 1 of those must come off.. how else would you get oil in it? pull a valve cover?

It looks like they are a set, 1 left and 1 right - that puts the breathers either both front or both rear and that is pretty cool in itself! I'd like to have them if I had a FE motor.. just use an early intake with the pcv addition and oil filler in front! It'd be a neat setup imho... 8-)

under edit.. I forgot to say welcome to the club! It good to see another blue oval guy around here! LOL..