BMW 168mm Limited Slip Differential: Restore and Elevate Performance Specifically designed for most 4-cylinder BMW models before 1999, the small-case (168mm) Limited Slip Differential has been a cornerstone for models like the E21, E30, E36, and Z3. Choose Your Pack: Service or Enhanced Stage Kits Service Pack: Return to that authentic differential feel with a 2-clutch set. Stage 1 - Track Pack: 2 clutch set featuring Racing Diffs' durable clutch plates, ensuring optimal grip and longevity. Precision-engineered billet steel cap. Ramp saver shim designed for prolonged differential health. Stage 2 - Race Pack: Aggressive 4-clutch set with Racing Diffs' enhanced clutch plates for a better performance curve. Pre-load shim set billet steel cap for superior strength and stability. Ramp saver shim and pre-load shim set for precise lock and improved handling. Stage 3 - Max Performance Pack: Aggressive 4-clutch set with Racing Diffs' premier clutch plates. Ultra-durable billet steel cap. Pre-load shim set multi-variation ramp set, allowing drivers to fine-tune differential behavior for optimal power distribution and road connection. To re-build your differential completely, you will need the Bearing & Oil seal set. OEM part numbers: 3314120380633-14-12-03-80633 14 12 03 80633.14.12.03.8063314120380333-14-12-03-80333 14 12 03 80333.14.12.03.8033314120380433-14-12-03-80433 14 12 03 80433.14.12.03.8043314120380533-14-12-03-80533 14 12 03 80533.14.12.03.8053314120415333-14-12-04-15333 14 12 04 15333.14.12.04.153