We bought a used toto from a bathroom remodel. After looking inside the tank, I am totally confused. I thought toto toliets had the 3" flush valve, but this one has a smaller one, maybe 2". And the flush assembly (don't know what the name of it is) is just a normal one with a big black floaty, instead of a gmax one. Both the tank and bottom say toto on them, but I am wondering why it has the smaller flush valve etc, and how can I tell what model it is? Thanks so much!