http://www.pbresource.com/KT-GFLIP03AM.html
"If your current plunger has a Tail, this was the original Gottlieb® design. This design was supposed to avoid plunger hangups. It turned out that the tail caused more hangups than it cured. Gottlieb® later removed the tail to correct the problems it was causing. Thus the above plunger is the correct replacement part for your tailed plunger."