The first Ambassador was a sedan that was sold from 1927 until 1937. It was a larger version of the Advanced Six.
The 1932 through 1948 Ambassadors were known as the Ambassador Eight. These cars did sell fairly well during these years (although not produced during the U.S. involvement in WWII), and Nash and GM were the only two car companies to make money in 1932 during the Great Depression.
The 1949 through 1951 models used the Airflyte body style and sold very well. Still, the cars did not have the refinement due to a rush to market following WWII.
The 1952 to 1957 Ambassadors are the ones that most people remember. There were restyled in every way and more rounded than previous models. They also had some luxury options that were very rare for their day, including a Weather Eye heating and ventilation system and an air conditioning system that would not be seen in some other American cars for another 35 years.
These cars are classics, and there is a large market of collectors who buy and sell Ambassadors and keep track of every little piece of information they can about these cars. If you are looking to buy an Ambassador, you'll want to research the price you should expect to pay and then check out the Hemmings catalog or, even better, check out the eBay listings. You'll be surprised the deals you'll find on cars and car parts on eBay.