As I said there are many variables. You could have got 5km up the road or 5000km. It could have been the tiny amount but you had it parked up a while to do your diffs. So a slow leak could have been enough that once you started it you bent it a little. Once its bent it will keep bending. Throw some load on it and it bends fsr enough to grab the the bore and snap. Then just breaks shit.