I had to do the oil pump on my cj2a and it took a pitman arm separator to get the gunky thing out. The problem is that the oil and filth have glued the thing in. If the engine was still operable, you could try running it and heating it up which would probably help. The distributor which was on the other end of the shaft wasn't much better.
A rag and an oil filter wrench might help give you some leverage to loosen it up and you'll probably have to just keep working it over and over.
