Steering wheel fitting on a Tuscan - spline or hex?

[Dischordant]

May seem like a simple question but I don't have mine to look at (and even if I did I'm not sure I'd know) - is the steering wheel fitment on the Tuscan a Six sided spigot that the wheel fits on to or a fine spline? Ordering an Isotta steering wheel and want to know what boss is required.

Many thanks!

[Basil Brush]

It's a Vectra B splined column.

[Dischordant]

Thank you =)