Originally Posted by witeshark
I have never heard of anything like that.
I notice that there is some oil on the cross member below the point where the drive shaft is attached to the differential. However, I did not see a particular place where it was coming from and since I have cleaned it there is no obvious leaking point.
Some older rear wheel drive vehicles had a pressure regulator valve that would activate to reduce pressure inside the differential especially during jack rabbit starts. Sometimes they got clogged up and did not relieve the pressure thus causing some oil to escape from the differential.