What would swapping the center section include doing as compared to the knuckles? And could I do that myself??
Same thing I suggested. Swapping the center section (aka pig, chunk).
It's like a third member and you can remove the hubs, spindles, and shafts and remove the center section(the radius arm may have to be loosened or removed for clearence). Replace, put it all back to together.
Or, just swap out the beams as a whole. And swap out the knuckles, which will require the hubs and spindles to be removed....
6 and half a dozen...
Which is in better shape? Was the new axle gone through and seals replaced?