cb750 vs cb500/550 speedo drive plate

hello, i am starting a dual disc conversion on my cb750.
i have to purchase a cb500/550 but Im not sure if the one i already have is for 750 or 500/550.
i am trying to google for the difference but cannot find any.

any help?

thanks
el__burro

i guess i was looking for the wrong part.
the one i need is number 9 not 15.
correct?

thanks
el__burro

Looks correct to me, looks like part 9 keys into part 1, but I'm no expert and have not done this conversion and nor do I own either bike. Many Hondas of this era had many common parts, should be cheap enough to take a punt on should you not get any further responses.

Actually I worked on a spare I found in the box.
Here's what I achieved.

It's a perfect fit.

Now I am working to stop the little spill of oil on the forks.
Thanks
El__burro