Replacing toilet syphon

[Tudor]

Hi people,

The diaphragm has split in my Derwent macdee metro 3 part syphon, single flush. Instead of fixing it, I am looking to replace the syphon with a whole new one that would provide a dual flush. I have uploaded two pictures of the toilet. Can anyone recommend a suitable replacement?

 

[Newboy]

Dudley duo / turbo 88

 

[HERTS P&D]

Just replace the diaphragm, forget the dual flush. You are just making work for yourself.

Andy