Im am certain I'd be looking for a used 3:73 front axle! Rebuilding that mess would aggrevate me to death! I'd be throwing tools around the shop and screaming explitives.
If you do choose to rebuild that thing don't spare the parts. And for goodness sake don't spare the cleaning. Just a few of them little metal dusts can cause seal leaks in unblieveable short miles.
Surely that thing was humming for many miles. One Jeep I purchased had a hole in the back cover from the inside out. (looked like a bullet hole) A bearing was thrown out of it..and IT wasn't in the shape yours is. I put new bearings and pinion seal in it and she is still on the road.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />