THE FULL STORY
The ref. 1625 was produced by Rolex from 1959 to 1977 in solid 18k gold, two-tone steel and yellow gold, and steel with a white-gold bezel. The best known feature is the engine-turned finish; combined with numerals, this model has an unmistakable appearance. 
The origin of the name "Thunderbird" comes from the nickname of the USAF Air Demonstration Squadron, established in 1953, which was the first supersonic aerobatic team. It started with one pilot wearing this watch, and eventually it became the team’s go-to timepiece. For Rolex, it was perfect for capturing the American market with this patriotic reference. This reference actually started production under the moniker of "Turn-O-Graph," a legacy naming convention for Rolex following the ref. 6202. For the ref. 1625, we find the "Thunderbird" naming much better suited for the watch, adding a layer of depth with the story of the USAF Thunderbirds.