It turns out that is the oil pressure relieve valve and not available on the 420 or the 560. It may be available on turbo charged engine.

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1991 420SEL Project Car (Completed and rides beautifully) http://www.peachparts.com/shopforum/showthread.php?t=112321
2000 BMW 740IL
2000 Integra Type R - Track Car - SOLD
2005 S2000 - Track Car
06 C230 Sport
89 560SL