yes it is, I had the first 50 series STS in my area. Best combine ever aside from minor design flaws. But this thing a bleeding pile of green goo. Worst is the support, if it isn't safety related I think deere doesn't really care.
Working for a harvester with 5 9660's and one has had more problems then others this year. However there is one problem that has occurred on the 96 and 97's and that is the reverser pulley on the left side of the feederhouse has worked lose and slid on the shaft. Deere is aware of this problem and has a improvement kit out to solve the problem, may be something else you want to look at when the dealer is out.