the 1973 Firebird Formula SD-455 was listed by Pontiac as getting built with the twin scoop Formula hood. They didn't though, and they got the T/A shaker hood

The car did not arrive with the twin-scooped Formula hood ordered, but rather the Trans Am shaker hood. Pontiac made the switch on purpose, actually. There were so few Formula SD-455s built that, to simplify emission certification requirements, the Formula SD-455s got the same shaker as the Trans Am.

https://www.hotrod.com/articles/1973-pontiac-didnt-want-firebird-formula-super-duty-455/
https://www.hemmings.com/magazine/mus/2016/07/Formula-for-Preservation---1973-Pontiac-Firebird-Formula-SD-455/3749884.html