In the driver's foot well, where the steering column goes through the firewall there is a rubber bushing. That bushing will either dry-rot or disintegrate with age. When it does, it will allow a lot of left and right, up and down movement of the steering column, and a very severe rattling and vibration when hitting bumps in the road when driving. It’s fairly obvious if you just stand outside the car and grab hold of the wheel and shake it. If you feel a lot of excess movement, 9 times out of 10 that’s where the problem lies. It's indicated as #23 in this illustration:
Kneel down outside the car and shine a flashlight to where the steering column goes through the firewall in the driver's side foot well. If there is movement there, and some obvious clearance between the hole and the steering shaft, this confirms the failure or loss of the steering column bushing.
Occasionally the bushing can dry out and you’ll hear a groaning or feel a resistance and vibration through the steering column. If you are experiencing that, spray some WD-40 or silicone lubricant onto the bushing from the inside of the car and move the wheel left to right until the groaning/resistance goes away.
If the bushing itself needs to be replaced, there are TWO ways to do it. The bushing is installed from inside the car:
1 - Park the car with the steering straight ahead. Disconnect and remove the universal joint pinch bolt from the bottom of the steering column. (This is located outside the car near the power brake booster). Access is from inside the driver’s side wheel well. Remove the access plate over the brake master cylinder and remove the center pinch bolt from the lower shaft. After a generous application of solvent, spread the lower steering column slip joint allowing you to collapse the lower column so that the upper joint slides off the steering column shaft. Remove the securing nuts and bolts holding the steering column to the bottom of the dash, disconnect the 3 electrical plugs for the various switches that are on the steering column, and remove the column from the car. Install the new bushing in the firewall and then reinstall the steering column. Be sure to orient the wheel as it was when you took it apart.
2 - There is a shortcut to the above. Rather than sliding the lower column slip joint together and then removing the entire upper steering column, try the following. Park the car with the steering straight ahead. Disconnect and remove the universal joint pinch bolt from the bottom of the steering column. (This is located outside the car near the power brake booster). Access is from inside the driver’s side wheel well. Inside the car loosen the steering column adjuster and pull the steering wheel all the way out and down as far as it will go. This gives some limited access to the bottom of the column where it goes through the bushing. From the bottom working inside the car, pull the inner column (This is the splined steel bar about 3/4" diameter, NOT the whole column) into the car (and out of the pinch bolt joint that you loosened at the beginning). This inner column can go all the way up into the collapsible outer screen of the steering column, allowing you to move the base of the column to one side of the hole in the foot well box. Install the new bushing in the firewall and then reinstall the steering column. Be sure to orient the wheel as it was when you took it apart.
Revised DAS 6/23/2016 [more detail, removed cut method, added shortcut]