I'm trying to bring my 67 RS with an original 327/210 back to as close to stock as possible. Found the correct dated 2 barrel manifold and original air cleaner, and have a line on a rebuilt Rochester dual jet, but can't seem to find out anywhere why some cars were set up with a positive system (vented oil fill cap/breather) and others a closed positive, with the pcv valve attached to the fill tube. I looked at the Chassis Service manual (fig. 10), but it only shows examples of the set-ups. Would appreciate any help.
My car has an early June '67 build and did not have a/c, nor the AIR system.