From my understanding the 13/14 GT500s have a larger pinion bearing compared to the any of the other Mustang 8.8 rear axles housings. This is why I was trying to find a 13/14 GT500 axle housing. I was planning on having the axle tubes welded to the center housing during the course of building a rear.I have a stock 8.8 that I may part with but to be honest, any good upgrade will weld the axle tubes when installing 9" ends and a regular GT s197 8.8 is fine for that IMO.
Good luck.
-J