Chevrolet built specialty vehicles for years. This included the 1950s.
The department responsible for the COPO Camaros (called the Special Order and Fleet Department in the 1950s) built limited edition vehicles. Like the tri-5 windowed Sedan Deliveries.
My '57 windowed Delivery was made in Cleveland, OH the shipped to Kansas City, MO to be assembled.
My 150 Handyman 2-door Wagon was made at the same Cleveland Fisher plant, but sent to Norwood, OH to get assembled.
Let's not forget the El Morroccos made in the 1950s but they were made by a private party. Not GM or Chevy.