Ed, are you referring to the exhaust pipe to manifold?. If so, these bolts are not threaded into the manifold.. If you are talking about the elbow to manifold, you should plan to remove the manifold to repair, unless you have a lift and necessary tools.

I think we are talking about the same stud. On my 232, there are three of them. the one I broke is the one that is located on the frond side of the flange, is bolted from underneath and you can see the top of the stud flush with the base of the exhaust manifold (at least I think I have the right names for the parts).

For some reason I could not get a stubby 9/16, standard length 9/16 wrench to stay on the two-bolt flange that joins the exhaust tube to the short elbow. I could not even get a thin-wall socket to stay with a flex joint socket wrench.

So I moved up a layer because I could see all the bolts from underneath. I have the car up on 6-ton jack stands about 24" off the floor.

OK................so I have to
1) take off carb
2) move linkages
3) take manifold off ( does this come as one piece or is exhaust and intake separate ? )
4) media blast manifold
5) drill and tap broken stud
6) coat manifold ( what is best coating to look nice and last ? )
7) reinstall with new gasket
..........

Ed, the manifolds come off as a unit. What was the original reason for removing the flange?. I would remove the heat riser while this is apart. Most of them at this point are the source of an exhaust leak under the hood, which in turn , adds to the fuel vaporizing and causing vapor lock problems. A slight drill through the holes once removed, and use 7/16th's bolts with torque prevailing nuts. Unless something on the manifold assembly is broken, then clean it all up, maybe even have it sand blasted while it's off. Make sure you clean the crystalized exhaust flange gasket good, have the elbow surfaced for trueness before re-assembling. I would also recommend having the manifolds surfaced as a unit while they are off. Clean and inspect all the studs in the block, we use a tap in all the special manifold nuts and a die to clean all the studs. If any of the studs came out when removing, make sure that you use some kind of thread sealer when re-installing them. It is not uncommon for them to come out on the bottom, center. Spending a few minutes cleaning all the nuts and studs makes this job go back together MUCH easier, and gives a much better, even torque when re-installing. Removing the inner fender panel is also required. Shop manual is always a must, so refer to it regularly. Hope this helps!

Thank you for all the tips.

I was trying to remove the OEM exhaust pipe at the two bolt flange. I have a hole in the pipe, just below the flange and the entire exhaust pipe needs to be replaced from this point back anyway.

My brother pointed out that there were no holes in the exhaust system when I took possession so it must be my fault. I noted that I would have thought Hudson would have made an exhaust pipe that would last longer the 65 years.

That joint should not be studs, but just two bolts dropped down through the flange from the top side. Perhaps someone tack welded the head of the bolt(s)? You should be able to see the head of the bolt looking down from the top. With the pipe removed, try carefully, tapping the stud with a hammer to see if it will pop out ?

Thank you, Dave. Interesting. There are three points of connecting holding that main flange the manifold. Two have nuts. The third (and the one I broke) has what looks like a stud. It is flush to the main body of the manifold, on the front side, right near the coil spring.

OK ED,
That portion of the manifold isn't normally removed in order to replace the exhaust pipe. since you did.. You have created a problem. My advice would be to remove both manifolds as a unit. Do not try to separate them. Take the assembly to a machine shop where they have several methods to remove and replace the stud. You will need to contact Dale Cooler and obtain the gaskets to reinstall the unit.
Ouch!

Yep, I know. It was the next logical item since I could not get a wrench on the block side nut of the two bolt flange that connects the
main exhaust pipe assembly.

It takes a very long extension, and a six point socket.. From under the car. I know... Now we tell you! LOL