If you are looking for the very best F-fitting on the market check this one out. You can see in the photo that this a heavy duty fitting. You can check out the alernate metal F-fitting on the page painted a silver color for $19.00. The 66 intake has a pair of pressed in posts, that are 3/8" between center and rear carbs. Each takes a 3/8" hose that attaches to this fitting. The fitting exits to the passanger side where a 3/8" hose runs to the PVC valve in the valley pan. This fitting was orgiinally plastic. Heat and age have taken their toll. Also have a kit on the page to replace the rubber hose going from the F-fitting to the PCV valve.