I recently replaced all of the internals in my toilet's tank with:
400AKR Complete Toilet Tank Repair Kit - Toilet Flush Valve, Toilet Flapper, Toilet Fill Valve & Toilet Tank Lever
The fill valve made a whistling sound when the tank was filling so I contacted Fluidmaster and they replaced the fill valve with this one for free and had me send back the whistling one from the above kit:
400ARHR PerforMAX High Performance Toilet Tank Fill Valve
Anyway this was my first time doing this and I am happy with the results. Thsi old toilet has always worked well and I am glad I have it instead of a HET. Yet I have no idea who made it. When I had the tank off, I tried to find a label or stamp on who made my toilet. There is nothing I can find anywhere on it other than inside the tank.
There is a stamp that says 1 JAN 7 1986
and there is another one that says 56
. In the bottom of the tank near the bolt at 4 o'clock, there is a number molded that says 589
The tank lever is a Fluidmaster
replacement (not the one from the above kit) and the seat is a Bemis Whisper Close
I took the time to search the Internet for a few hours trying to figure out who made this and what the model is without luck other than finding this forum.
Here are some pictures: