Catalytic convertor gasket question?

[Darkside]

I am restoring a '84 GN. In its past someone welded a test pipe from the square flange on the downpipe to the y-pipe. My question is there a gasket between the square flange on the downpipe and the square flange on the catalytic ocnvertor?
Thanks

 

[TType84]

wasnt one on mine..

 

[Darkside]

Thought that might be the case.
Thanks