Second photo shows the 3 - Fittings that were available. I no longer sell the center pictured F-fitting, I sell the top pictured metal F-fitting and the lower pictured Nylon f-fitting shaped like a Y.
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 passenger side where a 3/8" hose runs to the PCV valve in the valley pan. This metal F-fitting will last a lifetime. I have specially made at machine shop . Also have a kit on the page to replace the rubber hose from the F-fitting going to PCV valve.