I used the factory PCV setup on my 261, which uses the stand-pipe Jerry mentioned. I did not tap into the air cleaner for make-up air but rather used a filler cap with oil-soaked metal gauze for a filter. I figured that's what the factory put on for the road-draft setup so it was probably good enough for the PCV. Wrong. This works but only up to a point, that being if you run zero vacuum for more than a few seconds you can start to smell blow-by. As soon as the vacuum comes up to say 2"Hg the odor goes away. If there's no vacuum in the manifold the blow by will come out the breather; whereas with the road-draft system even at zero vacuum there is enough draft from the air moving by to create a draft so the blow by goes out the road-draft tube.
This is probably not an issue on a truck driven around town or on local farm roads etc. where zero vacuum rarely occurs but on a highway rig where you're pulling long grades at full throttle it's a problem. I will fix it when I get home from the long road trip I'm on.
