David S., the shape of the grill housing, (side view) has two angles, some around here refer to that style as a Zig Zag. I believe the older engines have a better torque curve and can do more work with less HP. While I don't know all the details on it I've heard that it is due to some EPA regulations that caused redesigns of small engines. The first Cub Cadet only had 7hp and it would power a 36" mower deck a 36" snowthrower, it could pull a 10" turning plow.