Observation & possible solution (LSD)

[PipeUy]

The concave shim? How much backlash it has on the right side output flange? The left side has none?

Did you measure the total stack height of old and new clutch stacks? This will tell how much wear on the old one. But the new one is not OEM so it's apple to orange.

when turning the clutch stack will slip and make some noise, but should not chattering noise.

Backlash was not measured but it was considerably less than before, left has none like before.

The stacks were not measured because on RacingDiffs page it's mentioned that their stack is taller than the original one, so measuring them would not give any relevant information.

Yeah the sound is the clutch stack slipping and you can feel that, it's trying to "grab".