Lift up righthand side hood. Look at the front side of the block where it joins the cylinder head.
Flat area about 2 inch long x 1/2 inch deep
Serial number stamped into the face you may have to clean the dirt to read it
post the number on here and I will date your tractor for you.
If you want the date of build, post the casting numbers off the block; gearbox & rear axle.