hello Hacienda Esperanza,
while the radiator is off, do yourself a favor and Flush the engine block coolant area with a garden hose that has a nozzle on it. do top and bottom inlets several times.
I recently did radiator repair on mine, $54.50 was what the repair and a gallon of antifreeze cost me. i did flush the engine block at that time, and it took 15 or 20 minutes before clear water ran through. keep switching from top to bottom to loosen all the "Gras Dous" for a good flush.
oh, i pre-measured coolant before adding = 1/2 gallon anti-freeze 1 gallon water should top her off.
Pre-Mixing coolant before adding it to tractor is a good idea since we have have no water pump to circulate coolant for mixing.
edit: "Gras Dous" speal'un chould be ""GRAS DEUX" , get ur dunn !!! I thunk,....
Rhett