I was driving to work today and I happened to park behind a dump truck while waiting at the red light. I noticed that the axle are monstrously huge. The ring gear probably is 12 inches or something. Then I thought, it ll be hella cool if it was under a xj. Granted the minimum size of tires probably should be at 38 inches or something lol.

 

38's would be too small for that axle even imo, as far as strength and ground clearance goes. Gearing would probably be an issue too, the lowest geared truck Ive driven only had 4.10's in it, which was pretty low for a big truck. If you're doing something that you need a ridiculously strong axle, 2.5 or 5 ton Rockwells would be my first choice, not one of those axles.
And personally, I wouldn't put Rockwells under anything unless I was running 46"+ tires.

 

I didn't know that, I just estimated 38s would be smallest, I guess not lol.

 

Yeah, a normal 11R22.5 semi tire is around 42" tall iirc. 11R24.5 is even taller.

 

you wouldnt have to worry about breaking it under a jeep.... 16 inch ring gear, 45 spline shafts that are 1.75-2 inch diameter....... but the gearing would be lacking.... i think the lowest ive seen in a normal dumptruck would be 4.10s, some of the smaller trucks with auto do have 5.57 ratios though....

 

Someone posted up a picture last week of one of those housing broken in half that was in a Rock Buggy over here. Can't find the picture at the moment.