Fitted with the narrow end inside the column outer tube and the fat end pressed up against the bulkhead: (Haynes)

The later seal used before the full energy-absorbing column (RB cars and all V8s: (MG Experience)

The right-hand end fits over the outside of the column tube, the step preventing it going too far:

As well as the left-hand end being pressed up against the bulkhead the short narrower section protrudes through the bulkhead to locate it:

The later full energy-absorbing column BHH1596 with a clamping plate at the bottom, shown as part of the assembly in parts lists. The rubber seal AHA8720 is more or less the same size and shape but is separately listed:

There is a flange on the seal (B) that protrudes through the clamping plate (A) then both are slid onto the end of the column outer. This allows the seal to be clamped to the bulkhead while the column can be moved fore and aft on its slotted mounts to line up with the column UJ: (Moss Europe)