I just had a short shaft (slip yoke eliminator) kit installed on my XJ. It has 3.5" Rubicon Express lift kit.

Should the axle be shimmed to improve the angle? Here is a pic:

Is it vibrating? If not, I'd say leave well enough alone. If it is..then you know what you need to do.

doesnt look like it needs shimmed at that angle, but could just be the ngle of the pic. try to take a straighter picture.