560 SEC How do I recognize a “real” 560s???

Hello friends, would like to buy me a 86er 560 SEC, also have one today for the test drive. How do I recognize a real 560er? Not that someone wants to turn me on a 380er, 420er or 500er as alleged 560er. Come from the US-Car Scene, Mercedes is still new. Danke in advance for many helpful answers and tips… VG Marco