I can't remember if the 108 had any heat shields on the mufflers or not. I had one of these work loose and it gave me the same rattle.

Of course it could be anything but this is easy to check. All it took was adding one self-tapping screw to bolt the thing down tighter.

If a heat shield is there then remember: These will flex since they are not made of case iron, just a thin sheet of stainless. But they should not wobble and be firmly attached to the car.