This is a picture of my axle housing that JT has posted here, in order to solicit some response.
I have not been doing any jumping with it, and I don't know what the previous owner(s) had done with it. The crack had been repaired before I got it, as was evident from the poor welding.
It had cracked on me once before, and I did an arc welding repair on it (hence the red tape over the brake cable), but clearly not good enough.
This problem does not appear to be unique, on one of the other fora I subscribe to, there are a number (at least 3) other 80's that had similar problems.