A transmission engineer at Livonia Transmission got back with me quick. He called it an "Accumulator Spring". I think thats the technical name, but it's part of the "Intermediate and Overdrive Servo" from what I gather. It takes a special tool to install (must need to really compress that spring).
I just called a trans shop in Farmington Hills who said this quite common for the ring to rust and the groove to pit, and it just falls out. He said it should be less that $200. Hopefully he's right.
AAA is on their way to my house right now. Oh well, it could have been worse, my wife could have been driving and gotten stranded. Then I'd really hear it:)
