Funny enough I went to one right across from my work & he scrounged around looking for the down pipe side of the cat & found a rusted old pos so I passed. I'd like to get some new ones but Internet search has gone null. Lol
any decent exhaust shop will be able to order you the flanges you need. or you could take a piece of steel and make the front flange and buy a ball socket to do the rear..
the front flange could be made in a few minutes with a drill and a jigsaw with a metal bit out of a piece of 3/8" steel- laying out the holes would take longer than actually making it- the rear is just a common ball flange that any good exhaust shop or parts store will have sitting on the shelf.