Genuine OEM Volkswagen Differential Housing, part number 0A5409021G. This component serves as the protective casing for the differential assembly, which allows the drive wheels to rotate at different speeds. It is marked as number 1 in the diagram. The part weighs 16.651 kg and has dimensions of 0.29m x 0.29m x 0.22m. Genuine OEM differential housings are manufactured with precise tolerances to ensure proper gear meshing, lubrication retention, and structural integrity under load, which is critical for smooth and reliable power delivery.