How to determine throttle body size?

[Bad_Byte]

Ok this question may be silly but how do I determine the throttle body size?

Does it take an inside micrometer to measure the inside diameter or is it stamped on the body or coded in a model number?

Thanks in advance for any assistance.

 

[ewave]

On my 97 GTS I used a set of calipers to measure the inside diameter of the throat before the butterfly valve. It measured 60mm which I think is stock for these cars.

You can see the throat is machined to this diameter, as the machined surface looks different from the cast surface.