2022 general XP on the way
The grease doesn't go into the boot... that's a sealed (with the rubber boot) CV joint. The grease zerk in the pic simply greases the trans out put shaft so the driveshaft can float on the out put shaft...Someone may have over greased it, causing the fly-around.
To the OP it looks like the clamp is on the small part of the driveshaft, but I don't see it on the large part. Maybe the big clamp broke and all you need is the clamp?
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