The 629 Mountain Gun was first brought out as the Mountain Revolver in 1989 (actually a 629-2) only 5,000 of those were made. In 1993 was the first 629 Mountain Gun (these should be your 629-3's as the 629-4 came out late 1993) In 1994, another run of Mountain Guns came out in the 629 (should be 629-4's). More came out again in 1998 and 1999. The one you're talking about if it is the 1993 version should have a Rubber Grip (hogue), be a round butt and should also be drilled and tapped. All came from the Standard S & W Catalog 3rd Edition. They are a sweetheart of a gun, I have one in .45 Colt, and they are starting to gain interest, and the one you're looking at is a pre-lock gun to boot.