It can get pretty tight on a TJ especially when you try to push the axle back.
For U joint protection use a Ninth degree. AEV diff slider just make sure it doesn't gouge the drive shaft. With enough lift it stops being a problem because the pinion gets turned up quite a way with a cv shaft. I have scraped my front straps which has since been solved with a high pinion axle the rear has never been scratched even though it has belly flopped on rocks quite a few times