Sorry to hear about your father.
You've got a great tractor there.
Doesn't matter much if it has a 9N motor in it for using it.
If it still has the 8N steering and axle, you will need 8N parts for those.
8N front axle should have the radius rods hooked to the center section.
9N/2N radius rods would be hooked to the outer/adjusting pieces.
As SG said, you can tell if you have early or late style gearbox by looking at it.
If you want to know if the year is close, there are a couple of other things
you can look at that may get you in the ballpark.
Casting numbers on the rear axle. (probably most reliable)
A solid metal shifting lever, or a screw off "plastic" top?
Proofmeter in the dash, or the older style dash?
Take a look at John Smith's site for good identification info.John Smith
Best of luck!