You didn't say what year car. If you have a 62-67 you can get a lower bearing from Moss Motors. See item 26 in this Moss plate.
http://www.mossmotors.com/Shop/ViewP...eIndexID=29018
If your car is a 68 or later car there are no known sources for bearings. Gerry at GEM Enterprises make bushings to repair steering columns. If you have a rubber bumper car I believe you will need to send him your column. I have not used his products but he has an excellent reputation based on comments from users of his steering repairs/parts.
http://www.gem-enterprises.net/
Clifton