My father is considering buying a Colt Trooper Mark III, that is in 98% condition. It is a 22LR, 8'' barrel, satin nickel finish. Serial number Y171xx. He has been told this is a "rare" firearm. Can someone help me with the year manufactured? Is this truly rare? When searching the internet I have only found two sales listings for this particular combination, most are the .357 or with a shorter barrel. Any guess as to an offering price would be great. Thank you so much for the help.