So it sits in front of the bellows retaining ring and not on the drive itself? I've never put the adhesive on it and I guess why that's been my issue? I assume the castle you're referring to is the part where the ring fits directly above the u joints.
Yes, it is glued into the bell hsg, tight up against the bellows retaining ring. That slotted, "castle" ring is the retainer that holds the drive shaft assembly in place in the upper gear hsg. This slips inside the bell hsg. O ring, and the nose on the upper hsg compresses, and seals when the out drive is torqued up. If you don't glue the ring into place, that slotted ring can roll the O ring out of position.
I apply bellows adhesive, or contact cement to the bell hsg. bore and to the outside of the O ring, and let it cure tacky. Then I fold the O ring's top down and set the bottom in place, and unfold the rest into position. Then press outward around the O ring to get good adhesion.
The grease is my personal warm and fuzzy insurance. Not per manual.
