I'm wondering if it had something to do with the heat from the exhaust. I was plagued with leaks so recently got all new gaskets in her and finally all the fumes out the back. Only change I can think of.
I don't think it was the tank. Had just filled up so would have been some hell of a bang if that was the issue.
When I got the extinguisher on it at the start it seems to be the diff and diff bushings on fire but it was a bit of a blur after the adrenaline wore off