as rusty as that is and as much work as it'll need, I'd probably buy a clean whole axle and swap that in (always buy brakes/bearings/etc for the year of the axle as some things changed slightly over the years). but that's just me. I dealt with rusty parts for most my life and avoid it whenever possible. if you want, you can retain the current axle behind your garage, but there's nothing on it that would indicate that it's the original axle (as compared to another CAD axle). there might be a link to a writeup on swapping in later shafts in the link in my signature.
this is your CAD (central axle disconnect)