Drop-in decoder with top side on-board LEDs for various KATO Japan electric locomtoives The K8D6 is a 6-function drop-in decoder for KATO N-scale locomotives. The K8D6-A features two super-bright LEDs on the TOP side of the board for directional ligthing. This decoder includes connections for up to four additional lighting outputs, each with on-board resistors for LEDs.