I had an issue where my steering shaft was wiggling up, down and side to side, but only by a fraction of an inch. Enough to make the vibration of my warped rotors resonate throughout the dash and make the cab noisy when slowing down from high speeds. Although probably not vital, it was quite annoying.
After changing out my upper steering shaft bearing twice, there was one thing I noticed. The bearing didn't exactly "hug" the shaft, which seemed to be causing the source of the excessive play of the shaft in the column. To cheaply fix this, you could line the inside of the bearing, where it makes contact with the shaft, with a layer of electrical tape. The thickness of the tape is just enough to make the shaft grab the bearing and stay put. However, this is not a permanent fix and may need to be done again in the future due to the tape wearing down.
The only real way to fix this problem is to replace the entire upper steering shaft. The reason being, that the teeth on the shaft which grab onto the bearing become worn down due to age. They should have somewhat of a point, not flat (shown in photo). When sliding the bearing down the shaft, it should stop at the teeth and require pressure to fit the bearing around these teeth by means of a brass drift (lightly tapping around the inside of the bearing) or a section of small pipe which will tap down onto the inside of the bearing. Either way, the bearing should not just slide over the teeth loosely.
I myself am not sure as to what causes the wear on these teeth, be it normal wear and tear or possibly quickly taking a sharp turn or putting to much pressure on the wheel in one direction. If someone knows, I'm sure we would all like to hear of it!