Bad Vibration around 55mph

I am experiencing a bad vibration starting at about 50 mph. I followed the Haynes check and put the AW4 into 3rd, and the vibration continued. I lifted the front end and tried to check the wheel bearings. There doesn't seem to be a noticeable of the wear I have experienced with bad bearings. I then lifted the rear off the ground and put it on jackstands. I checked the rear driveshaft u-joints and found no play in those either. I drive this primarily on the highway, and I haven't yet had an alignment. If this checks out okay, what do I need to check next? I also plan to check out the balancing of the wheels as well. Could the front shaft be the culprit? It has the 231 t-case. Thanks

Jeff

the front drive line COULD be the culprit. Pull it off and drive it around. If the vibe is non-existant, you'll know it is the front drive line. It takes 4 minutes to remove and try out.

My guess is tire balance if you search around the site 55 mph seems to be the most common speed for vibes. I had vibes @ 55 mph tried rotating my tires the vibes were still there pulled the front shaft still there got my tires rebalanced viola gone. Oh yeah I was completely stock @ that time

I am going to try the drive shaft first. If that doesn't make it go away, I will take it in to have the wheels rebalanced. Would a bad wheel bearing cause this problem too? I lifted the XJ and worked the wheels up, down, left, right and didn't seem to have any play in the bearings themselves. Will definately try the driveshaft first, cannot hurt if it only takes 5-10 to take it out. Will keep ya posted. If it is the front shaft, what do I do next? Does it have to be rebalanced or what?

Jeff