Because the SPD is just a guess. There are two SPD's for all the A12 cars and we know all were not built in two days. If you have the original door panels look at the dates on the inside of them and that will get you closer to the actual production date of your car. Also the vin help in the speculation, but without factory documentation the actual build date would be hard to determine.
Getting old just means you were smarter than some and luckier than others.
