So sorry for your loss. I have had 7 GSDs and we lost our last one when he was barely 8 yrs old. We also experienced this issue with another one of our dogs, but we were fortunate to save him with emergency surgery. It is called torsion bloat and you do not have much time when it happens before...
Stress crack is probably the issue. I just had my windshield replaced on my truck and talking with the glass shop guys, they said this happens quite often. They said they just reolaced a womens glass that shattered during the night while parked in her garage. They also said that gorilla glass...
Probably the most useless gimmick ever put on a modern vehicle whether breaking in an engine or not. Depending on your driving conditions, it will actually use more gas instead of saving.
I have experienced the same symptoms as everyone is describing here. Not all the time but enough to notice. I assumed it was the driveshaft, but maybe not.