Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
Might be worth checking the downloadable Honda workshop manual on this site.My 400 has lock washers, a paired arrangement iirc.
Try this, (Attachment Link) RegardsDave
Actually looking at that service bulletin, it looks like CB350 had the lock tabs - 400 not fitted ?
Have they got the serrated flange Mick? If so loads available in stainless steel