One of the main differences between Rochester 2GV carbs was the use of the "hot idle compensator" feature found on Rochester 2GV carbs designed to be used with factory A/C. If the application was a non A/C car, then the carb did not incorporate the hot idle compensator. So, for your application, be sure you find a 2GV either with or without the hot idle compensator depending on whether or not your car has A/C or not.
A Rochester 2GV with the hot idle compensator feature is easy to identify by looking at the back (firewall) side of the carb as described in the following from Carburetor Models 2G, 2GC, 2GV Service Manual 9D-3, May, 1973:
During prolonged idling in heavy traffic in hot weather, under-hood temperatures can exceed 200 degrees Farenheit causing severe percolation or boiling of fuel in the carburetor float bowl. With excessive heat, all fuel vapors cannot be eliminated through normal venting and some will be drawn into the carburetor bore and intake manifold resulting in over-rich idle mixtures. The rich mixture causes a rough idle and may even cause engine stalling. The Hot Idle Compensator is used on some 2G carburetor models to off-set the enriching effects caused by these excessive fuel vapors by supplying additional air to the intake manifold when idle air/fuel mixtures become rich due to temperature increase. The compensator consists of a thermostaticallycontrolled valve usually mounted in the area above the main venturi or at the rear of the float bowl. The valve closes off an air channel which leads from above the carburetor venturi to a point below the throttle valves.
The compensator valve is operated by a bi-metal strip that senses temperature. At a certain predetermined temperature, when extra air is needed to off-set the enriching effects of fuel vapors, the bi-metal strips bends and unseats a valve which uncovers the air channel leading from the carburetor venturi to below the throttle valves. At this time, just enough air is added to the engine
to offset the richer mixtures and maintain a smooth engine idle. When the engine cools and the extra air is not needed, the bi-metal strip closes the valve and operation returns to normal mixtures. Hot idle compensators are pre-set at the factory and require no adjustment. However, to insure proper idle adjustment, the valve must be closed when setting engine idle speed and mixtures. This can be done by using a screwdriver to press down lightly on the valve for those models with the valve located in the main venturi
area. On those models with the valve located at the rear of the float bowl, hold spring-loaded button "in" when making the
idle settings. If no button is available, remove idle compensator cover and using a screwdriver, press in lightly on the valve when making idle settings. Replace cover after completing idle adjustments.
Over the years, this is the type of distinction that has gotten lost when you go down to the local parts store and try to find a "correct" replacement carb. GM/Chevy designed variations depending on application and options. Now you will get "the one size fits all" story from the local parts house, assuming that they even offer a "replacement" carb. Clearly, "one size fits all" was not how GM/Chevy designed it.
Other than that, if there is no part number stamped on the carb (either on the body itself or on a metal tag attached to the center front air horn screw), it is going to be very difficult to determine exactly what you have.
