So my 99 TJ had a 3" lift on it when I bought it in May. It's driven fine since then until it recently developed a vibration (in the steering wheel; trans and t-case shifters didn't move) mostly in 2nd and 3rd gear with a rhythmic, but not very noticeable vibration in 4th and 5th. After researching it appeared to be a u-joint issue. There was no movement in the rear driveshaft, but I still took it out and took it for a short drive in front wheel drive. The vibration was gone. So I changed out the rear u-joint in the driveshaft which did have some movement inn the two pinion that attached to the axle yoke (see pic). Put in a new Spicer 5-153x and the first couple drives were good. Now the vibration is back, exactly the same way with just a little less intensity. The new u-joint is move and right in the driveshaft, but the cross moves side to side in the caps that are strapped in the yoke. The caps themselves do not move and are mounted in the yoke properly. So why is the cross moving? That's the question.