Sorry to hear about your husband
I can't find the exact year but that model was made 1998-2005.
Can you find a VIN# on the tractor (like what your car has)? It's 16 or 17 characters long.
If you find that:
If it's 16 characters long, the 9th character is the year.
If it's 17 characters long, the 10th character is the year.