Toyota Repair: Steering column knocking sound, steering wheel, steering column

Question
I have a 94 4Runner SR5V6 with 61,000 miles.  There is a knocking sound that seems to be coming out of the steering wheel column at various times.  It starts to knock, sometimes for up to 15 seconds, then stops.  I thought that it would more frequently make the noises after making a turn but lately I can't seem to determine a pattern.  It comes out at low speeds, higher speeds and while waiting at a light.  What do you think is wrong?  Thank you

Answer
No TSB for that,
Can you give a better description of the noise?
when, where, type of sound, high, low,   etc.

a bad auto locking hub can transfer the noise up the steering shaft.
Have somone stand outside the vehicle during the noise and see if you can isolate left or right and see if its at the outer wheel area.

Mike