What is the Age of a S and W 38 Special CTG serial number D718603?

Call S&W and they can tell you when it was shipped. It could have been in the warehouse for weeks or months.Your serial number D718,03 indicates that you have a Smith and Wesson model 10,12,13,14,or 45 that was made between 1974-1975.The serial number range is D659,902-D750,000.Most likely 1975.