HELP severe vibration and pulls to the right

I have a 96 Lesabre and it has recently started pulling to the right and has a very severe vibration when i drive it. i haven't hit anything that would make the alignment bad. any ideas on what the problem could be. (it shakes so bad the steering wheel also shakes)

Look for a shifted belt in the front tires, or switch them to the rear and drive it, if the condition is gone, buy 2 tires.

thanks for the information.......I'll try your idea first