Fan spacer, measuring 2-7/8 inches, sometimes mentioned as 3.15" overall. Applications include 1967-68 Mercury Cougar and Ford Mustang with 289/302 and standard cooling. Reference number YA-79. Two styles were available, both styles are found on 1967-68 Cougars.
Ford part # C5OE-8546-A, Ford engineering # C5OZ-8546-A.