Exhaust Annoying Rattle!

My 87 VS had an annoying rattle, especially at tickover. Last year my regular MOT tester even thumped the exhaust at the end of the (successful) test as it was so annoying! - I promised to fix it for next time...
I replaced it with one salvaged from a donor car I bought at auction in May from WB & Sons (some might remember that car covered in dust/debris - standing in a garage for many years), so ideal opportunity to cut open & investigate. The attached photos show what I found. Interestingly, I cut open where I thought the rattle was coming from - & found the flat, round piece of steel as shown. It kind of looks like an old penny... not sure if it is an end blanking piece broken off from within the exhaust, or a punched piece left in from original manufacturing. Anyway, I was pleased to have found the source & thought I just need to make a plate & weld it back together. Then I picked it up & shook it... ANOTHER rattle! This time from the other side, so more cutting & part of an internal baffle support turned up! I don't know if anyone else has experienced rattles, hence posting. I'm unsure if the exhaust is factory. The pics are interesting themselves to see the internal baffle arrangement & also to understand how it packs an effective exhaust into such a small system.
Tom (Durham)