You are looking a a BRAND NEW General Motors NOS catalytic converter and y pipe for 1984 and 1985 Buick Grand National. 

Not cheap repop stuff, and still has the sticker and part number stamp on the y pipe and box for the converter.

I don't know when this was discontinued, but this is probably something you won't find again.

Catalytic converter part number 25056546 and y pipe is 25518391