A Body Steering Column Difference?

How do you tell the difference between a steering column with 4 speed/auto on floor for power steering and a non power steering a body? Are they different lengths? I was told there is a difference.

The power steering column is shorter then the manual steering column.

Any idea on what the length on the two are? I'v got one that I'm looking at, but want to make sure it is for a power steering unit.

On my '69 manual column its 10" from the lower bearing retainer to the end of the steering coupler.