No it's off the other exhaust I have, the one on the car is fine, but the other cat back I bought is missing it.
See, I bought a straight pipe cat back, but I don't want to fit the whole thing. Be much easier to just swap the back box around come NCT time rather than the whole cat back, but, that that cat back is slip jointed, so there's no flange on the back box pipe if you get me
What I was thinking of doing when I bought it was to cut the flange off the new center section, and weld that onto the back box, but the flange that came on the exhaust (at the downpipe side) is the one that the donut gasket goes onto...not the flat one that it should be for a back box.
So ideally, what I'd need is, either the flange from a back box, or the flange from the back box side of the center section, cause I couldn't imagine anyone having a back box flange lying around...but as colm said, an old broken center section or something would do, just cut the flange off that.
Does that make sense? Tis a bit hard to explain lol