95 Cherokee rear differential

I have a 95 cherokee, 136k, w/ the straight six 4.0 and manual tranny.4wd. Pinion seal went out in the rear differential. The gear lube got low and it got VERY hot and I stopped after about 5 miles from first smelling something. I refilled the gear lube and had significant noise. Not a grating but a hum that was consistent w/ speed and no change w/ gear shift. Drove about 50 miles home and the sound continued. Once again, the sound increased in pitch and volume with speed and nothing else. I have now torn down the differential to the mushroom shaped gear in the far end. Axelshafts and other gears are out. The driveshaft is off and the pinion oil seal is out. The action on the spindled rod attached to the mushroom gear is smooth and doesn't catch anywhere. However, I can move the entire thing maybe a millimeter or two. Not a lot but certainly noticeable. I could also cause the same movement when the driveshaft was still attached by gripping and moving it. The universal joints were solid with no movement. My question is what is the rule for the spindeled rod and its play in the differential. I also have extensive wear in the brake drums and feel the noise may have come from there partially. I cannot figure out how to remove the final gear and rod from the differential and so cannot inspect the bearings and sleeve to check for damage. I really don't want to put it all together and not have fixed it. If nothing else, how do I remove the final gear from the differential housing. I have stared at if for quite a while and I just don't see it. Just a large gear on the inside and a rod sticking out the front with it all locked in somehow.
thanks a lot and bless you.
matt :(