Boeing 377-10-19: A single example was built and flown as the Stratocruiser prototype. It was sold to Pan Am in 1950 and brought up to 377-10-26 standard.
Boeing 377-10-26: These were the twenty ordered by Pan American. All were delivered with round passenger windows on both decks and a rear galley.
Boeing 377-10-26S: Refitted with larger engines and named Super Stratocruiser.
Boeing 377-10-28: Originally ordered by SAS, but taken up by BOAC, four in all. Like the Pan Am aircraft, they had round windows on both decks and a rear galley.
Boeing 377-10-29: Eight were built for American Overseas Airlines. These had round windows on the main deck, rectangular windows on the lower deck, and a rear galley. Shortly after entering service with AOA in 1949, the line was purchased by Pan Am, and these 8 aircraft finished their passenger carrying careers with Pan Am in 1960.
Boeing 377-10-30: Ten were built for Northwest. They were built with rectangular windows on the main deck and lower deck, and a rear galley. All were retired by Northwest in 1959.
Boeing 377-10-32: Six were built for BOAC. They had round windows on both decks, but a midships galley.
Boeing 377-10-34: Seven were built for United. These had rectangular windows on the main deck, round windows on the lower deck, and a midships galley. In 1954 the surviving United Stratocruiser fleet was sold to BOAC.
377F - Freighter Conversion.
Guppy Variants: Many and often modified. Going to need to research this more.