Most honest shops wont charge you any different depending on the condition of the trans unless the case or differential is damage and needs replaced and then you will likely be told that additional fees apply. I have seen a few of these transmission make it will into the 200K+ mile territory but is not common to see. If your trans is working fine then I would keep driving it. Some live a long time and some dont, there is really no magic answer as to why or which ones and all you can do is drive the car and not worry about it until wear and age get the best of it.
