I bought a new exhaust for my na but a previous owner went and got a frange-less cat.

Now I have a small dilemma. I’d rather not cut the nice stainless flange off my new but a new CARB cat is really expensive. Is there a way to tell what kind of cat this is or how old might be? My car has 305k it so I have no idea how many miles this has. Are used cats a thing? Any knowledge on any of this greatly appreciated. Thank you.