New problem....exhaust outlet...fix?

[Shawn_of_the_Dead]

Okay guys, I have a problem with this outlet tube from the exhaust. It is attached to nothing, and is applying a thin coat of carbon to my engine bay...also melted together a wire or two. Anyway, I was gonna take it off remove the piping and plug it (was told a nickel would work prefectly, and not melt or leak.), but it's rusted on there pretty good. Can I get another one of the threaded collars from an auto parts store, or nissan? Does anyone know of another way to take care of this? Enclosed a few pics for reference.

This is the rusted collar I am trying to remove:
http://img270.echo.cx/img270/7119/dsc025377vr.jpg

This is the metal tube spewing out carbon crap:
http://img270.echo.cx/img270/3579/dsc025362tb.jpg

Another pic, same collar, different angle:
http://img270.echo.cx/img270/8864/dsc025354ie.jpg