I will try the crowbar method first. If not I have to order a 46mm wrench. With the exhaust dropped but not removed it would still be hard to turn the nut. I would have to cut the bolts at the exhaust manifold and I dont see how I could remove the studs and retap without taking the head off. The manifold to head bolts are also rusted beyond recognition. A simple method would be to sawzall the exhaust pipe at a convenient location and reconnect with a union and clamps but I hate to hack my car up. I'll report on my progress. Thanks for the input.