I have a Jeep Twin

Question

I have a Jeep Twin Umbrella Stroller Model #55110-JJ Manufactured in 5/2004. I am looking for the part to the seat belt that snaps into the lock to hold the child in. It is a pressure release piece. It is threaded onto the belt and is 3 prong. The piece fell off somewhere and I am unable to use the stroller without it. I have tried to get one of these parts everywhere Please HELP