8 1/4 vent tube

I picked up an 8 1/4 out of a 76 Duster.Having always had 8 3/4 these are new to me.There is a vent tube instead of the vent brake hose bolt like the 8 3/4 has.It was cut off but moves freely(comes out).Where does this end up at and can I just plug it and use one like the 8 3/4 has?