Any pictures of the tractor as a whole?
For us average joes (without a dealer connection or ability to decode the serial #) we have no idea what model that is from.
I believe that block is a 201CI 3-cylinder used in the 4000-series
And while that does indeed look like a serial number, the D in the front isnt jiving. Should start with a C or B?? But I am no ford expert. There should be a flat somewhere around the starter with a serial number similar to that, as well as a model code, and a date code. Is there anything there around the starter??