So just a final update on this thread, the bastard motherf$%#ing starter is out... I ended up paying a mobile car mechanic to remove it with the help of a cutting torch and a BFH. It took him two hours, so I feel vindicated that a professional couldnt do it quickly.
It ended up being what I suspected, the steel stud oxidized on the aluminum case of the starter. I had tried the various suggestions here, but my little propane torch wasn't enough. I even managed to lift the front half of the truck with a jack under the starter.
Either way, she starts up amazingly now, huzzah.