Why would you wanna shorten the housing? Are you building a drag car? Have you narrowed the sub frame and installed have rear tubs for super wide tires? If not pop that center section out, align the splines, reinstall center section, install axles. If axles are damaged order some new ones up from dr diff.
Not full on drag car, but definitely some wider tires are in order. I figure since everything is apart. Why not??? Maybe some 10" cheater M&H slicks. Tired of my 7" bias wide ovals just lighting up and not going anywhere. No tubs or mini tubs if I can avoid it. Just thoughts.
If you are not going to mini tub it no real reason to narrow the housing. Unless you have a specific rim that you want to run that requires it for the wheels to fit....