I believe its a 1956 TD-6. My boss bought it, ran it for about 10Hrs before the a steering clutch went out. Replaced both ran it another 10hrs, and the motor went south. Had a neighbor rebuild it best as we could, but couldn't find a good head for it. He had as many of the cracks as he could welded up. It ran alright, but needed the fuel tank pulled off and cleaned or replaced. It would plug up the fuel filter in no time. I just got tired of working on it constantly, and its been parked in a barn for the last 5 or 6yrs. It needed some serious TLC, and someone with more patience than me.