Ford 8.8 is the most popular its 5/8 narrower the a wrangler but will work great. They can be found in a lot of Ford vehicles. If you for a 96 or newer you get disc brakes. 87 to 88 XJ limited have a Dana 44 there not as strong but they don't have C clips. With a little fab work you can get the Ford 8.8 disc brakes on the 44. The Dana 30 upfront is a good front end and doesn't need to be replaced unless your going to run 38" or larger tires. If you run 35 or larger I suggest you get rid of the CAD and do solid shafts possibly mollys. I run 36 13.50 swamper iroks with the d30/d44 set up with molly shafts up front 4.88 gears and E-ton electric lockers. I built my jeep for one purpose rocks, and never had any brake downs in the drivetrain department. Ok going for my second Rubicon run in a few weeks.