The most common place on a saxophone to find its serial number is just below the thumb rest. The early Selmer’s saxophones had the serial number on the bell and back of the body tube. In this case, use the serial number on the bell to date your saxophone.
Usually, the serial number on a saxophone is located on the opposite side of the body tube from the low D key. The serial number of a saxophone can be used to find out when and where it was made, and sometimes by whom it was made. Brand-name saxophones have serial numbers that are easy to find and read.