Kohler flush valve seal can not find a part number

[wpatters1229]

I have a kohler two piece toilet F78275 which has a flush valve rubber gasket that has a 3" ID and not one not even in a chat with Kohler can come up with the correct part number. The part number I keep getting is for a smaller seal. One that has a 2 5/8 ID.
Does anyone know the part number for the bigger-diameter seal?

 

[Twowaxhack]

Post pics of your old gasket and a pic looking into your tank

Your old seal may be stretched out

 

[wpatters1229]

I may have found the seal at home depot. It is for a class 5 and 6 toilet and says 3" I am going to go there with my measuring tape and check.

 

[Geofd]

There should be #s in the tank in most cases only 4 printed in black or cast into the china

 

[GReynolds929]

I can't find that model in my Kohler parts book, or their website. Like @Twowaxhack and @Geofd said we need pics of inside the tank. If you have a canister flush valve that is not a dual flush, the seal is GP1059291

 

[wpatters1229]

I may have found the seal at home depot. It is for a class 5 and 6 toilet and says 3" I am going to go there with my measuring tape and check.

Got the seal on Amazon and it works!! Also Kohler sent me under warranty the whole valve assembly just in case. I installed the yellow seal last night and it actually fits and works.