Hi Jay. Apart from a leaking radiator I just discovered in one of our 940s, my New Year is off to a good start. Hope yours is, too.

I haven't been able to discover much more on the exhaust header to cat coupling My collection of service manuals (aftermarket) simply says to use a sealing ring if one was present before and all diagrams show a sealing ring present rather than a gasket. Rather obvious unless you're presented with a situation such as yours.

To answer your question, yes, I am suggesting that your ANSA down pipe was likely for something earlier like a 740 non-turbo. Although it's not clear from the parts house listings I saw, the 940s may well have always used a sealing ring. The gasket setup was certainly not uncommon in the earlier non-turbos.

So you're thinking of cat surgery to get a proper mating. I'd think consulting with a vet would now be more appropriate than seeking advice here. I, too, would be hesitant to pound on the cat any more than is necessary to avoid injury to its guts. I would at least want to heat its end cherry red before peening the so called flared protrusion from the feline. Be kind and go heavy on the anesthetic here. You might also want to think about using two gaskets, even trimming one as needed to better fit the battered pussy. When you're done, your 940 should be purring like a kitten .... oh, alright, enough of that.

FYI The TSB I recalled seeing was actually announcing a special tool to drive out broken/damaged press bolts from the flange without removing the cat from the car to a shop vise. It suggested heat and a hammer as an alternative. It would appear that press bolts were not always present on fixed flanges. I'm guessing it eventually dawned on someone that just using regular bolts was cheaper and simpler in the long run. Press bolts were likely never used on floating flanges -too hard to replace. The B234F revised exhaust system I mentioned was for unification of B230FT and B234F parts back of the cat. This was simply a matter of standardizing pipe diameters, but if you replaced one B234F part with a B230FT part you had to replace them all. Although the on-line parts houses are not at all clear on this, I don't think the cats were ever exchangeable (probably an overall length thingy).
--
Dave -940's, prev 740/240/140/120 You'd think I'd have learned by now