Large oil seal which goes between the Haldex transfer case and the rear differential is the main reason of premature clutch wear inside the Haldex and rear eLSD. If the oil seal is broken and leaks, oil is moving freely from Haldex to eLSD chamber. Oil pumps can't create enough pressure to operate clutch stacks normally and they wear out fast.
It is strongly recommended that you change it on the drivetrain service as Haldex oil and rear eLSD oil shouldn't mix.
If you need a Haldex reparation setor a rear eLSD reparation set, you will require this part to complete the job.