I installed an Energy Polyurethane dust boot on an upper ball joint and I'm not sure how the big end is retained. It looks like it just slips over the ball joint body, but it flexes and slides around as the uca travels up and down(exposing a little bit of the ball joint body). There are no instructions included. I know I've got the correct part. It seems like it should be held tight up against the bottom of the uca.