Sounds like the exhaust pipe to manifold donut is blown or gone.
A new donut is cheap, but the fix can get ugly.
The two bolts/nuts that hold the pipe to the manifold will not want to come out. As I remember they should be a 5/16-18 thread and will want to twist the stud off. Then you will be pulling the exhaust manifold to get the broken stud out.
I would first try warming the engine up to where the bolts are good and warm, then quench the nuts with pee oil while they are hot, but not too hot to catch the oil on fire. I prefer Kroil but PB blaster is also good.
When it cools down, give them a try. Not too much though, the studs will be rusted pretty bad where they go thru the clamp.
If you don't twist them off and they still don't want to turn, hit them with pee oil again and let it sit overnight.
Next day heat the nut fast with a propane torch or better yet a acetaline torch to make the nut grow faster than the stud, then try them again while hot, before the stud gets hot.
Hope this helps some.
Here is also the link to the reunion in KC.
The show is the Midwest all truck Nationals and we'll have our oun area to gather, BB-Q and talk.
https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1020166#Post1020166Just be there, if your truck can't make it, that"s ok also, just bring pics and stories
