I wonder if you could adapt something w/ longer bolts and springs so the joint seals but can move. See the first jpeg in the second post here;
https://www.allpar.com/forums/thread...ctions.163374/
Here are some parts
https://www.amazon.com/Walker-35129-.../dp/B000CQBG1O
Google this "spring bolt exhaust joints" for a bunch of pics and search results