Adapter loco board L-shape like 6090x, with AUX3 to AUX6, for 21MTC (not MKL) decoder.
ESU 51968 Adapter Plate For 21MTC Interface AUX3-6 New
ESU 51967 Adapter loco board for use with LokSound/LokPilot NEW in original...
ESU 51968 21MTC Wired 21 Pin Adaptor PCB With Aux3/4 Outputs 6090X
ESU 53950 Adapter board for LokSound L / LokPilot L (Screw Terminals)
ESU 51957 Adapter Board 21MTC 8 Enhanced Outputs Solder Pads + Cable NEW
ESU 51959 Adapter Board Giving Connections For LoKSound / LoKPilot L decoders.