Thanks guys. It's the muffler, or actually the common exhaust chamber that combines the left and right exhaust manifolds prior to the exhaust pipe. The exit pipe connection to the chamber is rusted through. Completely disconnected. The heat shroud (which no longer has any use) is in bad shape as well, but not unserviceable.

Besides Plane Exhaust, Aerospace Welding Minneapolis has been recommended.

I've seen other modifications done to the exhaust systems of CallAir's. I don't think they were approved.

David