Mike there is a trick. Take the drive off and pull on the shift cable clamp out of the drive as far as it will go. Then get in the boat and move the shifter untill the cable from the boat sticks out as far as it will go. When pushing on the drive get it close then manually by hand close the clasp around the cable. Push the rest of the way. If it binds either turn the propshaft so the drive can shift or have someone in the boat move the shifter to take up some of the cable.
You really need two people. I tried it alone and brke stuff on the boat and injured myself.