There are a lot of different types of transmission fluid. Is that what you're asking?
There is a member here who is well schooled on the makeup of such fluids.
Just to be clear, you cannot use just ANY "transmission" fluid in your tractor. There are lots of different fluids that are called, "transmission fluid". They are NOT interchangeable.
If you are not read up on the differences, stick to what Kubota recommends.