I have a kohler K301 on my c120 . I need a piston and ring set for it. When trying to order it on line they can't identify the engine with the spec numbers on the factory sticker. I know the tractor is a 1975. The speck # on the shroud is 4752237 and the serial # is 1525265651. Not shure how to proceed with this and order the correct parts Thanks Bob