DUH! You guys are taking a very narrow minded approach to solving the issue of the track bar hitting the diff. Yes, adding longer bump stops can keep the track bar from hitting the diff. However, since he doesn't have any lift. Adding longer bump stops are going to limit his suspension from compressing to the point he's going to end up with a really shitty ride.
So the after market track bar I use is the JKS' HD track bar.
https://jksmfg.com/collections/wran...-lj-cherokee-xj-comanche-mj-grand-cherokee-zj
On the their website they state under important notes that "TJ Requires 2.5"+ Suspension lift." I run a 4 inch lift which gives me plenty of clearance between the track bar and my Poison Spyder bombproof diff cover which is significantly thicker than the stock cover. I only had to add enough bump stop to keep the tires from hitting the fenders.
This is also why I do the majority of work on my Jeep myself. It seems there is no limit to the number of installers that take the same moronic view above that keep people bringing their Jeeps back to the shop on a monthly basis instead of fixing someone's Jeep correctly the first time around.