Yes. The HG was discontinued and the OC-3 introduced durring the same year. I will need to look because I was thinking 1952. Paint wise the first OC-3 tractors were green same as an HG.  In fact I was to a man's place and he has 2 OC-3 tractors. The older one is green the 1953 is yellow and I have seen 2 1953 models that are yellow and they have the letters IND on the serial number tag.