I have a Colt MK4/Series 70 Government Model. Serial number 60156B70. I also have a Colt .22 Conversion Unit. I am in the process of possibly selling or trading these units but the serial number never shows up. I need to know when these items were produced. Can any one give me any information on these items and what they might be worth. Both of these pieces look brand new as I hardly ever used them.