The key to this one will be failure analysis. Unfortunately, I'm not sure where you can find someone to help you. I used to work in Warranty with heavy trucks. So I regularly worked with Eaton and Rockwell field techs on determining failure modes, mostly for their drive axles.
Wheel hop is a killer in our 5 speeds that shocks the driveline. This can, and does cause failure of the transmission output shaft, the drive shaft, u-joints, or even yolks. Your failure sounds extremely catastrophic and not typical of other people’s failures. Usually the output shaft twists off inside the tail housing of the transmission and you just don’t go anymore. For the rear housing to come apart, it sounds like you had prior damage to the tail housing that weakened it. Thus when the wheels hopped and the driveline was shocked, the energy rather than being absorbed by the housing, caused it to fracture.
What you would want to look for is signs of stress fractures that may have been there before. Thus with stress fractures, the part isn’t broken, but it’s breaking. And it gets worse each time it is stressed until it finally lets loose.
If you haven’t regularly beat on your car with wheel hop incidents, I would be suspicious of the paint shop perhaps taking your car for a test drive.
