Mio, PM Sent.
I just got a call from the neighborhood trans shop. This guy is NOT a Bimmer specialist but they did a decent job with my old clunker and have a 2-year warranty.
The guy says he only pulled 2 codes off of the car (of course he had cleared them before calling so I don't know the #'s). Anyway, he says that he is just pulling a bad torque converter on the trans. Since it is a sealed unit he cant tell any more internally without taking it apart. He says he thinks the seal at the back of the converter went out, and that was the loud "boom that went off like a cannon" that our friend, the owner witnessed. According to him, "this is a common failure in these cars."
He is quoting $1100 to change out the TC, and then they would do further exploration for damage while the trans was apart.
The other item he detected was a bad coolant temperature sensor which he said would cost about $40 to replace.
Other than these codes, the car is "immaculate" in his words.