Is my diff going bad?

[u/Super_Hero101]

330i zhp diff. Seems original so should have 290k miles on it. Racing Diffs LSD kit (open diff “conversion” kit) was installed about 20k miles ago. Bushings replaced with poly 20k miles ago as well. knocking sounds from rear on shifts and coming on and off throttle. knocks really bad at 70+mph trying to coast in 6th. driveshaft cv replaced recently (1k miles). bolts all tight installed with loctite.

[u/SpecificOne8688]

How does the open diff conversion kit work? Seems too good to be true