FAA Class 3 is good for 36 months if under 40....
FAA Class 2 is valid for 12 months, then reverts to a Class 3 for a further 2 years (very sensible in my opinion).
FAA Class 1 is valid for 6 months, then as a class 2 for a further 6 months, then a class 3 for a further 24 months as far as I can remember.
I think ECG is required at the initial class 2 IF over 40, otherwise its when you reach 40.
EA