Deck Plates for 1997 Sunbird Neptune

[familyofphillips]

I havea 1997 Sunbird Neptune and the deck plate near the transom, just in front of the motor is a pry out kind. The O ring is stretched and will not let the deck plate reseat properly, thus allowing water in the hull. I tried several boat shops here in Tallahassee, FL. today, but no luck. Apparently it is an odd size. It is a little over 7 1/2 inches wide. Anybody with ideas on finding a O ring replacement or a deck plate replacement without having to cut a larger whole for the new type of plates.