Put a add a leaf which moved me up about 2" in the rear and inserts in the front on my 96 XJ Country Now I notice a vibration from I think the driveline when under mild acceleration especially going up a long hill or when accelerating hard from a dead stop.
Sounds like a deep "hum" and I can feel it on the floorboards.

 

You need to get a Transfer Case lowering kit.

 

Hmmm...even with that little of a raise?

 

Vibration under acceleration is generally caused by two things. Ruling out any issues with worn drive-shaft u-joints.

Cause 1. Improper pinion angle.
Cause 2. Axle wrap.

The add-a-leaf is most likely causing axle wrap due to the rest of the spring pack being worn out. Worn u-joints will make the vibrations worse.

 

So if it's axle wrap would the lowering kit help?

 

No, not at all. Check for play in the drive shaft first. A lift will aggravate any slop and make it worse.
The see axle wrap try this on a level surface, have someone else in your jeep start it, press firmly on the brake and put it in drive. You watch the axle pinion/drive shaft from the side. Does it jump upwards when put into drive? Go from drive to reverse, you may see the pinion rotating a good amount. Also in 'drive' with brake applied, give it a little gas, does pinion continue rising. This is axle wrap and the only solution is replacement leaf packs. A very slight rise in the pinion is normal.
Add-a-leafs are notorious for causing wrap because they are often installed on worn or weak springs.

 

Thanks for the help.

 

Does it hurt to run the rig this way for a few months? Winter is still with us and don't want tot tackle this in the ice/snow.

 

Problem is the vibrations add stress and strain to the entire driveline including pinion seal and bearings and out-put shafts. Occasional vibs are one thing, constant vibes will cause problems.
I figure if you feel the vibes in more than one place (steering wheel, seat, dash, floor, shifter) than it's a bad idea.
If you have the 242 transfer case, running it in '4 Full-Time' will likely help. This will split 40% of power to the front axle.
Another option, with the 231 TC, is to remove the rear shaft and run just the front drive-shaft, IF your transfer case is one that will not pour fluid from the rear output-shaft. Many have driven like this when necessary. Drive a little easier when doing so. The front ring & pinion is smaller/thinner than the rear.