Rattle rattle - if it is not the heatshields, what then ?

[Wret]

I had an exhaust rattle that only occured when the engine was warm. It would go away in minutes so finding it with a rubber mallet proved fruitless. I gave and replaced the most likey suspect, the muffler, with a used one. The problem went away.

I have since dissected the muffler. There was nothing obvious flapping around in there. Maybe a baffle rubbed a certain way when the metal expanded.