Yes Jaba, you're thinking of the C441. The C421 is the C414's big brother - engines are about the only difference. Those geared GTSIO-520's are expensive to run/maintain and only have a 1200 hour TBO (which can be upgraded to 1600 with a new cylinder part number) if I remember correctly. Pilots have to manage decents so that the prop never drives the engine otherwise you end up witha stuffed gearbox.
Its that same reason we don't see more Twin Commander 685's etc flying around.