l wanna buy an extra key to my Infiniti G35, and found a web site StreetKeys.com that sells the key blanks at considerabley less than a dealer. But for the 2003 model year, it has 2 choices: G35 Track Model, OR G35 built before 07/03. How can l find what year/month my G35 was made? Is there a code on the engine block?

there should be a production date on the drivers side door or on the door well on the same label where it tells you your paint code and asembly orgin

You know when you open the door to get into the car, look down, and you see a barrage of colorful stickers? Among them should contain the information of when the car was built. It is usually in MM/YY form (i.e. 07/08 means July 2008).

Open the door and look at the stick in the door well or on the door.
It tells you the birthdate, tire pressure, and birthplace, and more.