[LTDzak]

I would try a large ring clamp, this is actually a Ford approved fix for loose catalytic converter heat shields. If that does not do it, stainless steel flex joints are avialable from several sources - OEM ones tend to be triple wall (with the inner wall being fairly smooth).

Now if someone can identify the large chamber in the exhaust near the fuel tank, but forward of the rear muffler, that would be interesting.