I am going from the factory 2.47 on my '91 560SEC to a 2.65 because I'd like more grunt from the lower end, and don't mind scrubbing a bit off the 152 mph I once saw on my car as it is now.

The vintage AMG Gen II catalogue, on its differential options page describes the available ones as going from the "mild" 2.65 all the way to the "neck-snapping" 3.46, (with the other available AMG diff ratios being 2.82,3.07 and 3.26)

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)