screw in direct cistern valve replacement

[fiddler3]

Leaking toilet - needs replacement flush valve but existing screws direct into cistern not fixed with nurt and seal.
How do I get this type of valve or is the thread size the same as the spigot and nut type so I get one of the latter and dispose of the nut & seal?

 

[ShaunCorbs]

Picture please ??

Many thanks