Surprising to fail a C6 - I've had several vehicles with one(pickups, LTDs, station wagons) and have tortured the hell out of them without any sign of problems even after pulling large travel trailers and 5th wheels

'Twere me, I think that transmission would have to come apart if for no other reason then to make sure nothing else is broken or that there are no broken pieces "floating" around. When that gear broke, there was a shock transmitted to other parts that may also be ready to fail. And the torque converter - a good 'core' for trade in and might be the opportune time for a different stall speed if needed or wanted.