Fogive me James, I think I am being a little bit dim today
You probably have a coupling like this on the end of your column ?
If you have, I guess the most low cost way of doing things would to do the following.
Cut the pice in the photo, midway in the round section ( Circled )
Extend the shaft using some suitable, thick wall round tube.
One end should then join onto the steering shaft & the other end should fit into the triangular end of the Sierra type group 4 coupling.
Still best to check with RD to see if this is the case though
