My Dad's last tractor was a Fiat 540 DT Special that he bought new in the early 80's. It was a 54hp tractor. The DT referred to the fact that the tractor was a 4WD and the "Special" meant it had hand PTO clutch, as opposed to the 2 stage clutch on the non-Special models.
When dad sold the farm, and ultimately the tractor, it had 8885 genuine hours. It was still a great tractor and had heaps of life left in it.
Dad used to rack up around 500 to 600 hours per year. He had looked after the tractor in line with his philosophy that "grease and oil is cheaper than spare parts."
It is quite conceivable that the Kubota in question could have clocked up 13173 hours, if it has been well maintained.