There should be a pin for the front bushing fits around the universal yoke and a pin in the bushing a few inches behind it that fits around the driveshaft. An Oakie bushing assembly replaces both bushings and the seal. The procedure is to remove the front bushing and drive the Oakie bushing assembly in the front. The driveshaft bushing and the old seal remain in place. If the pins are missing, maybe somebody has installed an Oakie bushing. They don't need to be pinned because they have and interference fit inside the tube.