Certain models of American Standard flappers use a float on the flapper chain to regulate when it closes. I would find a real plumbing wholesaler who sells American Standard toilets and order the correct OEM flapper for your model. There will be some numbers stamped inside the tank. Write these down so you can get the correct flappers. I install after market flappers a lot of the time but sometimes they just don't work right.
Hello all. Just wanted to post my latest update. I installed this weekend a Korky flapper with the float on the chain and things are looking good. It is flushing in one flush, no need to hold it and no more long multiple flushes. So far it is doing the proper job. Thanks again to everyone for all your help. Greatly appreciate it. Hector