The infamous "haystack Holley" a.k.a. the "teapot Holley".
The carb has a horrible reputation (very undeserved!) because of those who are unable to read the owners manual and perform simple maintenance, and the internet parrots.
One of the more reliable Holley carbs ever built. Many actually have ball bearings holding the throttle shafts to the main body to minimize wear. The first carb I ever built was the un-governed version; built when I was 14. The rebuilt lasted about 200k miles. Like most Holleys, the carb is extremely fickle, as it falls in love with each new filling station the driver attempts to pass.

As previously mentioned by others in this thread, the governed versions were used on trucks.
The identification number will be stamped on one of the vertical edges of the mounting flange. Look for the word LIST, followed by a series of letters and numbers.
Jon.