Those $12 stud I bought won’t work as I was going to press them into the flange the other day and the aftermarket flange holes were larger than the stud. So I will stop by the hardware store on the way home to see about getting some regular 10 grade bolts.
The other option would be to weld the stud to the flange.
But I think the hard part will be where the converter bolts to the crossover pipe. Those bolts look especially nasty and are on studs that bolt to the pipe flange it’s self ( engine side )
Everything looks pretty accessible so it may not take forever.
My theory is that there is a head gasket leak somewhere that causes the cat to fail in the first place. Also explains the over heating and consumption of coolant a few months back. But I can hope to get a couple more years out of it as a daily Driver. Will update this evening on progress. It will likely suck.