http://www.youtube.com/watch?v=WfPleGYBbZY
Here I show what I'm trying. I removed the lock bolt, and tap on the shaft until it stops, then turn the gear 180 degrees and tap it back the other way. I think it is getting to have slightly more movement, but only barely detectable amount.
I have been thinking about putting the cover back on, and filling the case with vinegar and rolling with it for a dozen miles, to dissolve rust. But the truck is not yet running so I'd have to hook up a tow bar and disconnect the drive shaft and pull it, which sounds like a lot of trouble. Another thing I've been thinking about is putting the lock bolt back in, turning it to the side that doesn't have the lock pin, and drilling and tapping a hole and perhaps use a slide hammer to get it out.