Question to ask yourself is:
Who knows you have a Satoh tractor?
It's not the kind of thing a thief would take on the spur of the moment. Someone KNEW you had a Satoh, KNEW where it was, and KNEW they would have time to unbolt it and steal it, and NEEDED a steering box or knew they could sell it. A steering box is not the kind of thing you take to a pawn shop to get cash for. It's also not made of exotic alloy or worth enough in scrap to just sell to a junkyard.
Thieves who steal farm machinery would most likely have taken the entire tractor to resell- no titles, no licensing, no VIN numbers in computers to mess with.
The average sneak thief would be more likely to steal the battery or drain the fuel tank or carry off anything in the shed they could easily sell for scrap metal.
Someone stole JUST the steering box...that means the theft was a specific, targeted job against you.
Figure out who it might be, and you might get back your steering box.