Hi Paul
Not sure about that one. I fitted a 10 speed Shimano onto an 11 speed hub and that was a 1mm spacer. If a 9 speed is the same width as a 10 speed then you will be ok.
Thanks David – a 1mm spacer worked. Amazed that Evans didn’t have them in stock – had to order it in. Hardest bit was removing the cassette I’d tightened in an attempt to close the gap without a chain whip. Did it with an old chain and some cable ties after seeing a Youtube video.