ML430

None specific to the M-Class. It's the basically the same engine and transmission used in other MBZ 430 models and in fact is built in the same plants in Germany. The only M-Class specific changes to the engine deal primarily with the intake manifold being "reprogrammed" to provide a different torque curve better suited to an SUV over a passenger car. As for problems, the transmissions seem to be very reliable. You should make sure the harmonic balancer has been replaced with the latest updated part, otherwise it's prone to self-destruct, taking about $2K worth of other parts with it. Of course you can also count on the "usual" engine maintenance items like bad MAF and O2 sensors, but like I said, nothing ML-specific.