That is the Teflon stuffing tube liner. When they are just stuck in they move. Most remove them and just run metal on metal and lots of grease. The trouble with Teflon liners is they wear thin and get hot and soft and wrap around the flex shaft and lock it up tight and aren't coming back out and you have to rip the entire driveline out and replace. Square drives aren't as hard on the liner as round collet where all the force pushing the boat is transferred up the cable.
Last edited by danielplace; 06-23-2017 at 12:44 PM.