I have a 1973 model 60. In the research I have done this is the last year before Marlin changed the feed throat design, allot of complaints between 1970 and 1973 about miss feeds, double feeds, etc. I know I can replace the rifle for $160.00 all day long but I love that old gun. I am very handy with tools and I have completely disassembled the gun, action included. I have replaced a broken hammer and anyone who has taken the action completely down knows that is not the easiest of tasks. In 1974 the feed throat design was changed. Does anyone here know what all is required to upgrade my rifle to the new feed throat with out a complete overhaul of the action.