Unkown in-wall toilet need flush valve

[kyleg00]

Hello all,

I'm not having any luck figuring out the toilet manufacturer. I have attached a few pictures.

I have replaced the fill valve with a THU-134, but the flush valve also needs to be replaced. I took the unit to one of the local plumbing supply companies and they said they've never seen one like this before. I've tried several replacement valves, but none have worked so far. They are either too big or small.

I've tried multiple variations including doubling up like in the attached picture.

The original valve at the bottom of the unit was black.

Any help would be greatly appreciated!

 

[Geofd]

Kind of looks like a style Kohler makes,the name on the toilet is usually behind the seat, is there a name on the fill valve?????

 

[breplum]

Not Geberit, not Toto. Seems to only leave Kohler? But I can not match it to any.
Pic of the flush plate and use google lens? Share a pic of that plate