The second generation Mercury S-55 was introduced for the 1966 model year. The second generation S-55 was offered as a two door hardtop or or convertible, and for the 1966 model year, the S-55 was a stand alone model. Due to poor sales, for 1967, the S-55 became a sports package for the Mercury Monterey. The second generation S-55 was powered by a 7.0L (428 cu in) V8 engine, and was in production until 1967.