SHC wrote:

The SD1 has one of those between rack and column, then a universal (hardy
spicer) further up. I'd say the rubber is to take up slight tolerances,
and the universal to allow the wheel to adjust up and down.

OK I think it's definitely a rag joint I need,

I've just taken one off a MK1 Escort rack that you can have for the cost
of the postage if you want. It's not pretty but looks sound. I'll take
some measurments this evening if you like.