I tried shimming also, which worked okay until I hit a large pothole, which jarred the subframe enough (old bushings) to compress the telescoping joint and eject the shims. Subsequently, I installed a steel collar w/ set screw over the outside of the telescoping shaft. Tightening the set screw compressed the outer shaft into the inner shaft, taking up the slop in the joint. Has worked great for about 2 years now.
IIRC, those joints are around $120 new.
-Nate