 These were built on the GM B-body platform and featured different styling from the more conservative Streamliner.In 1950, the Catalina pillarless hardtop coupe was introduced as a "halo" model, much like the Chevrolet Bel Air of the same year.In 1952, Pontiac discontinued the Streamliner and replaced it with additional models in the Chieftain line built on the GM A-body platform.