I did my initial tranny fluid for the 400 hour interval. When I removed the main rear drain plug- I heard a plopping sound into the container. After the fluid had drained, I fished a ball bearing out. I took it to my local kubota dealer and the mechanic had never heard of it happening. He indicated to figure out what bearing it came from it would be approx 100 hours labor. I have never noticed anything wrong with the operation of the tractor. I am not inclined to spend $2000.00 to figure out where it came from. What are your thoughts on my options. Thanks for your assistance.