well, you have spark plugs, spark plug wires, Distributer cap, and rotor button. all needing replacement between 30 and 100K depending on design.
coils, ignition controls, be it points, or induction pickup, crank trigger, computer contorller etc.
then there's the fuel management. map sensor, maf sensor, oxygen sensor, injectors themselves, if any of these fail, tracking them down is a problem.
the motors themselves are similar, and the longevity when maintained seem similar to other MB motors.
but the maintenance is higher on a gasser.