mid late 52.
mines 504xxx
sn starting for that year was:
1952 442035
soundguy
mind you.. that's the engine vintage. since all 1939 thru 1952 8n-9n-2n engines, and the similar 119ci flathead industrials from pumps and gennies all would swap.. it just tells you engine.
you can look for clues on the tractor to further id it as late. like steerinmg box, and most importantly, hump in trans. then again.. all that stuff will swap too. axle date codes can help.. etc.
post a pic of her from the side.