It probably had a starter generator on it. The picture shows one on a 1969. It is not the same SG as a cub cadet because it turns in the other direction, which is good because they are easier to find. In later years PK used a Kohler engine with a smaller starter mounted on the side where the coil may be mounted. Check and see if there is a small hole 1 1/2" on the side away from the carb.which the starter shaft may have gone thru to hit the toothed flywheel. It would be right in front of the coil in the picture.