New type of toilet tank overflow pipe?

I just bought a 2 yr old house and the toilet whistled everytime it was flushed. Bought me a Fluidmaster Whisper Fill Valve and Flapper. Installed the new fill valve but the flapper was not needed because this toilet bowl had a round plastic overflow pipe and the "round plastic flapper substitute" lifts up, the tank drains, then it settles down on a large red washer (about 3 or 4 inches in dia.) to stop any more water going into the toilet. The top of this fill pipe has a screw in cap that has a place to insert the refill tube. A short way down the pipe is a brackt sticking out from the pipe where the tank lever arm stick thru.
I have never seen this type overflow pipe before - hope I don't again - it leaks so very slowly in the washer area and then after enough water has leaked, the fill valve activates again. Think I finally got it to seat good enough that it doesn't appear to leak anymore.
What the heck is the name of this overflow pipe?
Can it be replaced (easly) with a standard fill pipe a standard flapper valve seat?
Thanks in advance.
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if it's old could be an american standard? brand visible anywhere? repair parts may be at home depot. easy means you have confidence, a secondary toilet elsewhere in the home, and it's 9am on saturday so you'll have all day to take it apart and revisit the store as needed and put all new parts in. replace every replaceable part now and use the fluidmaster "flusher fixer" you will love it too. we fix 20 toilets with fluidmaster parts. we love the fluidmaster parts. they will even send you free leak test tablets. see: www.fluidmaster.com
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