I'm after number 18 on this diagram. Please can you help with what I need or point me in the direction. I'm really struggling to find this part.

I have had a look for you and part number 16211-Z8D-800 is for number 18: Here is the link: https://www.lsengineers.co.uk/insulator-genuine-honda-part-16211-z8d-800.html