How does this shaft log get removed?

[Wind River]

I am working on my 1982 Hudson Force 50. It has been out of the water for 5 years or so now and I'm getting close to splashing. Previously when it was floating, I noticed there was a small bit of water weeping at the nuts that hold in the shaft log and the threaded rod they were screwed onto were rusting. I figured now is the time to take care of this but I am not sure how to proceed with this repair.

I want to replace the rusting threaded stock and figured they were threaded into a mating plate. One of the nuts threaded off like normal but the other was rusted to the threaded rod and the whole thing is spinning inside hull. I ended up grinding the nut off and now the rod is looses enough that it will wiggle up and down but even with vise grips attached to a slide hammer it will not come out or unthread.

I have ground away the fiberglass and resin that appears to help seal this connection hoping to remove the portion of the shaft log to get a better idea how to replace the threaded rods. There doesn't appear to be anything left holding it in place but it will not budge. I can see wood where I ground past the fiberglass so it doesn't seem like there is a mating flange inside.

I have seen where the ends of a stern tube is threaded and the flange spins onto it. If this was the case, why would it have the nuts holding this flange on?

Any help on how to remove this would be appreciated.

[Ballsnall]

Originally Posted by Wind River

I have seen where the ends of a stern tube is threaded and the flange spins onto it. If this was the case, why would it have the nuts holding this flange on?

The flange end of the stern tube looks like it is separate to the tube itself so I would assume it does actually thread on. Maybe the studs are just for security to stop it from turning or water pressure pushing it out.