I would take a long hard look at the R129 if you're set on an automatic. While I didn't own the V12, I thoroughly enjoyed my V8 Silver Arrow. Bilstein Shocks/H&R springs and Michelin PS4S really buttoned down the handling- still a comfy cruiser, but didn't fall apart on a twisty road and looked the business. Obviously the SL600 had the hydraulic suspension, but many convert. The later 5 speed autos are near bulletproof.
