EEE code found on logic board -- Q35,QBJ,RBV,RBY,S3L
Note: All Apple logic boards have a special three digit "EEE" code embedded in the logic board serial number which positively identifies the part. Please note that this is the serial number of the logic board, NOT the serial number of the machine. The logic board serial number is on a tag which has the format "xxxxxxxEEEx". The "EEE" code is the three letters immediately preceding the last digit of the serial number.