Steering shaft length

The columns are the same. The shafts are different lengths.
Don't worry about the missing nylon pin. It is just spru left behind from
the nylon being injected between the shafts. It does nothing. The working part of the
nylon is filled into a groove cut into the inner shaft. The holes are just a place for the nylon
to enter these grooves and the air to escape as the space is filled with the hot liquid nylon.
Once the nylon cools it becomes a solid bushing or glide for the inner solid shaft to slide inside
the outer hollow tube. This creates a two piece steering shaft that is collapsible and will not rust
together. Rusting together would prevent it from functioning properly in a collision.
It will slide. Some just have more resistance than others.
It sounds like yours is a stubborn one. In this case you will likely have to remove
the shaft from the column and slide it by prying while in a vise. I did have one that
was stuck like this once. Most are easier.
I found on the particular shaft that was stubborn I was working with was a clearance problem between the inner shaft and outer tube. It was overly tight before the nylon was even put
into it. I was able to get it to slide using prybars and a vise.