Denver, the WJ stuff is current generation tech and we have old gen tech. You cannot use your current brake calipers on the WJ knuckle. It is basically all or nothing. When you do this swap, you can no longer use the XJ tie rod. You will be back to old school seperate drag link and tie rod. Also note that the WJ tie rod is kind of low and vulnerable. I did a tie rod flip on the drag link and tie rod for a few bucks. But if my measurements are correct, the WJ tie rod is too wide by a couple inches to use on the D30 You will need to use new stuff for that. As for rear brakes, I used WJ stuff. It has about twice the braking power as the ZJ disc set up. However you will not be able to use the WJ backing plate, it will not fit the XJ rear axle. I fabricated a plate for it and welded it to the housing. You might want to take a look at the latter part of my build thread to see what all I did