Can anyone solve my Honda part mystery battle for me? Please :)

Posted by Dobb on Mar 05, 2021; 8:08pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Can-anyone-solve-my-Honda-part-mystery-battle-for-me-Please-tp4064405.html

I'm in a friendly back and forth with a group about what type of header pipe flange was stock on the 1977 Honda CB400F.
I've seen vintage photo ads clearly showing the common "ribbed" flanges on the 1977, but I have people who are telling me that the flanges were flat on that year/model, even giving me part numbers. The trivia is driving me crazy! Perhaps Honda changed flanges during the 1977 production?
Does anyone know the answer?
Thank you!
And BTW, hello, I'm new here from NW WA.