[Ironhorse]

After looking at the pic I would say that is not an original air breather spacer for the 67-72 trucks. Does not seem tall enough and the tube comes off at a straight level, not angled back and down like would be on an original. would originally be rotated back further towards the distributor. I see you are using a push-in style breather on the passenger side valve cover. That valve cover hole would normally be used to connect to the air breather spacer thru a rubber hose with an end fitting similar to a PCV valve which has a screened flame arrester pushed into the valve cover hole with a rubber grommet. The purpose of that hose is to draw off crankcase pressure and fumes up from the valve cover into the breather and on into the carb to be burned and exit thru the engine exhaust. As you have it now, the spacer being plugged off and using the push in breather cap is fine. Hope all that makes sense, maybe another member can chime in with a better explanation.