Concours rear axle vent for any 1967-73 Mercury Cougar or 1965-73 Ford Mustang. Rubber hose that attaches to the metal nipple on the top of your rear axle housing. Fits 8 and 9 inch rear ends. Metal nipple that screws into the top of the rear axle housing. AMK reproduction, 7/16-20 threads, 9/16 wrench size.
Ford number is C5ZZ-4022-B, but AMK and others list the fictional part number of C8ZW-4338-A. Ford chassis assembly manuals, indicate that this is part number 4022.