They did he same thing with the Single-Six and the Light Weight Single-Sixs. They did the same thing with the Standard Autos and the MK-I. Ruger has the policy of setting aside serial number blocks for different model guns. The Super Single-Six that has the same serial number that your gun has, minus the 'D' was made in 1965. Your gun was probably made around 1968, a call to Ruger will give you a shipping date. 'It's a Single-Six in the Super Single-Six serial number range. It is also in original condition, not converted to transfer bar. This one is has a 6 1/2' barrel and is in great shape. Some people like to collect these Rugers, that is why my dad bought it.
This is a duplicate serial number, it has a 'D' in front of the serial number. Item Description: Shipped in 1968 and shot very little if any. Item Name: FS 3 screw Ruger Single Six convertible - Duplicate serial numberĬaliber: 22 long rifle / 22 rimfire magnum