Is an xj front diff. a direct bolt on under a tj.  

plug and play!
just regear to whatever you need and bolt it up if complete.

i used the tj's outer knuckles, calipers etc.. i don't think you can swap the brake parts around. you should just stick to one rig type/year as there were some changes.  

If you're looking for a Dana 30 from an XJ shoot for a '92-'99 high pinion unit. these are non-disconnect axles, which mean they use a unit bearing hub instead of the problematic vaccuum actuated hub and two-piece axle shaft set up, like early models.

the 2000 and 2001 Cherokee Dana 30s are low pinion and will also work as a direct swap but the high-pinion will offer better ground clearance, better driveshaft angle, and is said to be slightly stronger.  

they all have unitbearings.
the nice thing about the CAD axle is the housing is very tough and you can use your wrangler's passenger side axle to replace the two piece model. remove the diaphram and replace with a plate. warn actually has a kit for this. it comes with a couple seals to make it work. or you could get your own seals and make a plate to cover the hole where the diaphram used to live.

i wouldnt let this get in the way of installing a CAD axle on your jeep.