If that is a real 8 3/4 A body housing you should find a good home for it. I see people selling bare housings for $300-$600 and they are getting really hard to find.
Put a chain around the leaf spring/axle housing on the side without the axle and chain it to a tree. Then put a come-along ratcheting winch on the problem axle. Take all the slack out of the cable and then put some tension on it. Next tap the axle outward with a deadblow hammer or regular hammer. It shouldnt take much effort to get it to move. After a couple hits check the tension and tighten if needed.