Anyone know the size of the small hole in the valve cover rubber grommets on a gen vi 7.4l 454? I'm looking to replace I guess what you would call the pcv valve and rubber hose that runs to the flame arrestor with K&N push in valve cover breathers. K&N makes them in 1/2, 3/4 and 5/8in push in sizes. Just want to order them once and not get the wrong ones. All answers are greatly appreciated.

Ryan