In addition, I think before the 55H factory hillside was introduced, there were one or more machine shop levellers put on in the early 50's by local inventors. My uncle had a Dave Neil leveller (possibly made in Garfield, Washington) on his first 55 which was originally a level land machine. The header swiveled where it met the cylinder instead of where the header auger met the lower part of the feeder house and I think the back wheels did not tilt and stay vertical on the hillside (made fun steering I guess with no power steering). It had a levelling cylinder only on the left side unlike one on each side like on the factory produced leveller. There may have been another leveller developed by another inventor too;maybe in Moscow, Idaho though I'm not sure. In the pull combine days, John Deere also had a smaller 33(I think) which was smaller than the big 36. The photographs on this site have a picture of that combine also. See Jim Marples Hillside Photos.