Minitrix N guage FM engine coupler conversion kit

[radio2]

I recently picked up two older minitrix FM engines with the standard rapido couplers , having already changed the couplers on one aquired years ago, I know Kadee (microtrains) makes or made one unfortunately I can not remember the number of the kit, Microtrains web site does not list a specific kit for this engine. Any help would be greatly appreciated