How do i figure out what year my porsche 912 is?
 

My customer recently found a porsche in somewhat decent shape in a barn, so My customer bought it for super cheap. Its a 912 and there doesn't seem to be a VIN, or at least not one like My customer is used to seeing these days. The only numbers My customer could find on it are on a tiny plaque in the door jam. The numbers are 455664 and 6608. The guy says he thinks its a 1966 and the numbers both have 66 in them, so My customer is assuming he's right. Can anyone confirm that for me?
MB STAR C5