(11621744323) - Copper Exhaust Manifold Nut -8mm (68 available)

BMW part number 11621744323 is a copper-coated, non-flanged metric M8 (M8x1.25, 12mm wrench size) hex locking nut. It is primarily used to secure exhaust manifolds, catalytic converters, and downpipes to prevent hardware from backing off under high heat. Because it is a standardized, universal fast-wearing exhaust fastener, it fits dozens of different BMW models (from 1968 to the late 2000's), many BMW motorcycles plus other German cars (VW, Audi, Mercedes, Porsche, etc). (6a)

BMW-wise, here's a list courtesy of Google AI...

• BMW 1602 / 2002 Series (E10 Chassis): 1968–1976
• BMW 3.0CS / 3.0CSi (E9 Chassis): 1971–1975 
• BMW 3 Series:
  • E21 generation: 1977–1983
  • E36 generation (318i, 318is, 318ti, 323i, 325i, 328i, M3): 1992–1999
  • E46 generation (323i, 325i, 328i, 330i, M3): 1999–2006 
• BMW 6 Series (E24 Chassis): 1977–1989 
• BMW 8 Series (E31 Chassis - 840i, 840Ci, 850i): 1990–1999 
• BMW Z3 & Z4 Roadster / Coupe: 1996–2000s (including Z4 M models)