I found this steering stem nut in the box of parts the previous owner gave me when I bought my 72 CL175. It's not the correct size for my stem so I have no use for it.
If you can use it, it's all yours! Just send me a message with your shopping address and I'll drop it in the mail (US Only).
It's an original Honda part, unopened until earlier today: 90304-415-000
This forum has been helpful for me getting up and running so I'm happy to pass this one on to another member.