Gas Tank Filler Neck Grommet Change

I don't know if this applies to you, but when I changed grommet on a new tank on my 72 Roadrunner, I ordered part number OER MF-296 from Summit. It didn't fit. I spent 2 hours, boiled it, used Dawn liquid, WD-40, dialectric grease. Pushed my fuel neck with all my might. The grommet is too small. Others made same complaint on reviews. I ordered one from Detroit Muscle Technologies. It fit perfectly and went in in one minute. Something to consider.