Originally Posted by Frank Reiner

The great installation advantage of the annular CV-joint axles is that they can be separated.
The inboard stub axles are first installed into the center section (diff), the end play checked and corrected if necessary, the rear cover reinstalled, the mount re-attached to the chassis, and the center section re-filled with lube.
The outboard sections (with both CV-joints) are then installed in the wheel hubs, and the inboard joints bolted to the stub axles.
With one-piece axles they must be compressed ~ 3" (or more) to clear the splines for removal or re-installation.
With two-piece axles they need be compressed less than 1" for R&R.