Hello,
I have a PERFECT FIT JCXJ84 Jeep MJ steering shaft. Could be the cure to your death wobble! Didn't end up having to install it in my Jeep, as there was no play in my shaft. We think this one might be a tad bit longer than the original, so that might be something to take into consideration should you choose to purchase it. This is an expensive part to come by, purchased from Rock Auto, but didn't try to install until a significant amount of time passed. Looking for offers, just want it out of my garage. It might fit XJs too - you'll just have to do some research.
Thank you so much!