you really helped and confirmed me in my choice of the axle. So I just ordered the GM 8.2 BOP shaft with 28 splines, the bearing and the seal at RockAuto. They had all the parts ready for shipping at a good price.
Yes, we were really lucky, that this happened at the traffic light. I was going very slow that moment, so there was not much momentum. It looks like a hairline crack that started to corrode to the inside. I did not feel anything unusual before. No sounds, no wobbeling, nothing. That makes it even scarier.
So I am looking forward to the arrival of the parts and hope all fits.