The 606 Hi-Clear is a continuation of the 460 Hi-Utility. You see the 606 H-C only once in the 1962 IH Buyers Guide. Why they changed the name to Hi-Clear remains a mystery. I've followed the 606 from the late 60's and wasn't aware of the H-Clear until 20 year ago when I stumbled across my first. I hunted down the owner and bought it. There are more gassers then the other fuels. I have a D-HC, as does the Huber Bros. in Wis. Jeff Foreman mentioned a third at the last Half Century of Progress when I talked to him. Unless yours is the one he was talking about, you have the fourth. I also have three gassers and one LP. If I remember correctly, the 656 utility w/ the straight axles and extended spindles, says "Row Crop" on the badge. Another mystery. Welcome to our small little club!