Leaky Petcock - wrong diaphragm for KZ650

Hello, on my '78 KZ650 the petcock started leaking so i ordered a rebuild kit for it and once taking it apart the diaphragm part that was original to the bike does not match what came in the rebuild kit. I have checked rebuild kits at a few different sites and they all have the same replacement diaphragm but it does not match and i can't get the new part to fit. Does anyone have any insight into this? I have attached some pictures, the first pic is the new replacement diaphragm and the last 3 are the original part and i can't find anything like this.

This? maybe? Looks like it might be an updated version.

www.partzilla.com/product/kawasaki/43028...6b5575de4884fc22fabd

 

In  the past there was a long topic on the kz650.info site about this topic.  Here are the part numbers I could find for the vacuum petcocks that came stock on the 650s from the earliest to the latest.

51023-1005
51023-1011
51023-1013
51023-1023
51023-1370
To the best of my knowledge the first one listed does not have the "top hat" looking part. I have attached parts list for it (1005)

I ;have also attached some pics showing the difference between the petcocks without and making use of the top hat item.
It would appear that the kit with the hat has been NLA since like 1999.

Lots of people have tried and failed to rebuild these fuel valves.
I ended up replacing mine with a Suzuki fuel valve with 44mm spacing.

Petcock - Vacuum - 44mm - Suzuki | Kawasaki and Suzuki Motorcycle Parts | Z1 Enterprises

I had the same issue on my 78 SR, I changed the tank out to an older tank from a 650B as I like that tank style a lot better. Rebuilt the petcock, it wasnt leaking  but the vacuum on/off wasnt reliable, it was either not working or going crazy full flow. I gave up and went with the adapter plate that allows for a 3/8" NPT petcock. This looks ok, but also a giant PITA as the one I got from Z1 sucks. It leaks also, from the petcock switch for lack of a better term. I ended up making my own gasket for it, and that seems to have worked, the thing i discovered is that the 3/8 is very common on old harleys so you can source those anywhere. I may spring for a pingle. They dont leak. Also I used motoseal on the bolt threads and the petcock thread. Seems like no matter what way you go, you have to really pay attention to the details and seal the holy hell out of it sadly. the old one previously didnt leak, with no sealant and only the factory o ring, and that would be my preferred method. 

good luck man