Phil, in all the years that I have been working with autos, I have never seen a fire caused by a gears or bearings. I have seen diff gears heat to the point of welding together, but not set the seals or oil on fire.
This has intrigued me since the first one. I would have suspected the hand brake being left on, to start a fire at the hubs, but can't see a binding gear or bearing doing that.
I mean the noise from a diff that was that bad, would be horrendous. Something else started the fire.
Harvey.