The piece that is missing has broken off
likely from vibration. It was originally one
piece like your other (good) side. You can
search for a replacement but as this was a
common problem it may take some time to
find one. Another option would be to get
some tubing and make the part that it missing.
You could make the joint behind the exhaust
manifold where it wouldn’t be so obvious.
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.