My 222000 mile XJ has a RC 3.5 N2.0 lift. The rear shaft rattles like a paint shaker when in "float" or no load on the road about 35 to 65 mph. I am about to go another 2" with coil spacers and some blocks for the rear. What will I need to do to the rear shaft to stop this. It is likely the output shaft and yoke are worn pretty well. It is avoidable by staying on/off the skinny pedal but I assume it will eventually tear something up. My thought was to try to space the T-case down some. Don't have the cash for the SYE kit so what do you think?

 

If you don't have the money for an sye wait and save until you do. Your already at the limit for the u joints which is why you are getting the vibration to begin with.

 

Sye kit. And many around here warn about using lift blocks especially aluminum ones on a xj. If I were you I'd get the sye before blocks and spacers since you obviously have a problem. More lift isn't cheap and you can't just throw on more lift without changing other components also. Lifting is expensive if you do it right and if you do it wrong it can be even more expensive.

 

Look up a hack n tap sye its cheaper.

 

if the problem is the splines and or the rear bearing or something like that then the hack and tap wouldn't help anything because it would still be on the bad bearing and bad splines.

 

Another option is to get a longer slip yoke. YJs had a yoke that is about 1" longer and more articulation angle than the XJ yoke. WJs (and I think ZJs) have a yoke that is even longer, with a harmonic balancer type weight on it that acts like a gyroscope and dampener combined.