I am interested in a Power FC that comes with a commander but the seller doesn't know if its OLED or the old LCD. The ECU its self is FD3S4, and I have the number off the back of the commander. Its FCC2ZG 000-0 0 3 7 2 . Anyone able to tell from this which one it is?

 

Most likely you have the LCD version unless it was purchased new from A'PEXi dealers after July 2010. My OLED starts FCC4 if that helps.
Ask the seller for the original purchase date.
ALSO LOOK FOR THE LIGHT SENSOR ON THE OLED. Post a pic