Originally Posted by ItnStln

I got that information from Wikipedia, but after I searched Google it seems like a 3C is good for Third Class Medical Certificate: A third-class medical certificate is valid for the remainder of the month of issue; plus
24 calendar months for operations requiring a third class medical certificate, if the airman is age 40 or over on or before the date of the examination, or
60 calendar months for operations requiring a third class medical certificate if the airman has not reached age 40 on or before the date of examination. I apologize for posting incorrect information.