I had the same problem on my '65. When I replaced the upper mast bearing it helped but it was still sloppy.

Upon investigation I found the lower bearing was gone (it is a ball bearing, the balls were gone blush) and the shaft was severly worn, worn to the point of being scary! This post helps to explain the repair:
http://67-72chevytrucks.com/vboard/showthread.php?t=399139

Hope this helps!

Last edited by Hot Rod John; 08/22/2010 11:09 PM.

In the Stovebolt Gallery ~~ "The Orange Crate" 1965 C10 SWB Step Side Build Thread

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