You discovered there are some differences in flush valve systems and that toilets sizes can vary. An easy reference is to look at the size of the flush valve drain opening in the bottom of the tank. If it’s about the size of an orange or baseball, you need a 2 inch seal. If it looks more like the size of a grapefruit or softball, you need a jumbo 3 inch seal. Let us help you get that fixed! Would you be willing to contact our customer service team? We would like to learn more about your toilet and quickly identify a solution. Please dial 1-800-528-3553 or email us at sales@lavelle.com. We are available Monday through Friday, 7:30 AM to 5:00 PM CST.