steering column question..

OK...Once again, I am rebuilding another steering column for my 68 'cuda. The new one I have now is a manual steering floor shift column. I found a couple differences in the two, that I wonder why there is a difference... The manual steering floor shift column has a larger tube diameter than the power steering column shift column.

As you can kind of see the difference in this pic:





Also, the manual steering floor shift column has a locking collar, shown in this pic:



The power steering column shift column does not have one...May I ask why is that? What dictates one to have one, and the other not to have a locking collar?

See what I have to work with!



I would like to get a new lower steering column bearing, but for 90 dollars, I'm forced to rebuild and clean up the old one! Any idea where to get the collar? Everything is heavily pitted!