faulty filler neck grommet?

Several years ago(many), I installed a brand new tank on my 80 Volare. It came with a new grommet. I could tell right off it was a bad fit and a wrong compound. It went straight into the trashcan. I reused that 1980 grommet, and it still works to this day,as it did, some 35 years ago. You can tell the junk by it's lack of lead-in chamfer,it's hardness/softness, and it's fitment.