The 6079 is based on the Glenfield Model 60 autoloader. Marlin produced the rifle at the behest of OTASCO (Oklahoma Tire and Supply Company) in 1979. Your serial number should begin with the prefix TK and there should be an "American Hunting Tradition" medallion depicting a buckskin clad hunter with a longrifle (smokepole).
You may want to give Marlin a call. They may be able to give you a count of those commemoratives made in 1979. Also, check out Col. Brophy's book, "Marlin Firearms - A History of the Guns and the Company That Made Them." It costs about $60 on the shelf of your bookstore but Marlin sells them direct to you for about $48.50 (that's about what I paid).
Gary
