(18301723883)(11751277998) - Exhaust Manifold Flange Gasket-320i (77-83) (2 available)

Part numbers 18301723883 and 11751277998 represent the exact same BMW exhaust system gasket.  I have 1 of each (let me know which one you want). Price is "per gasket". The difference comes down to a standard manufacturer update: 18301723883 is the modern, active part number, while 11751277998 is an older, discontinued part number that has been fully superseded. 

BMW shifted the numbering system for this component primarily due to material updates:

• The Original (11751277998): This was filed under Main Group 11 (Engine) because it initially sealed the junction closely tied to the engine block or manifold area. Older versions often relied on asbestos-composite materials common to vintage automotive engineering.
• The Modern Replacement (18301723883): When BMW reformulated the component to use modern, asbestos-free, heat-resistant composites, they transferred the part index to Main Group 18 (Exhaust System).