My steering stem nuts on the RD400's are rusty. Try finding them on e-bay - good luck! A forum member has one here in the U.S. that I'm going to buy. I was looking for more nuts.
Further inquiry led me to a guy in the UK who makes stainless hardware. $73 bucks including shipping bought me two stainless steel top yoke nuts with washers. That's about $37 apiece and they won't rust the way regular chromed steel hardware does.
If you want to contact Nick, here's the info: n.chambers53 AT live.co.uk
There's nothing better than fresh shiny nuts! :dawg:
Beats waxing...
Good idea to use some kind of thread lube with stainless hardware. It's bad about galling. Tiny dab of PTFE pipe dope or teflon tape.
IR8D8R
Not sure if they'll have what you need, but I've had good results and great service from https://www.allensfasteners.com/
Picked up a bunch of chrome hardware from them for my SOHC Honda 750.