So 12" of lift, are you in Hawaii?? Anyways so if i under stand you right your u-joint caps? are moving in the yoke?? If so i would get a new joint (don't cheap out get one from toyota) and see if that fixes it if you put the joint in and it moves around still i would look for a other yoke. make sure your d-shaft is in "phase":
http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html
