The DN163A1 is a board replacement decoder for Atlas N-Scale SD60, SD60M, SD50 and others.
1. Carefully remove the locomotive’s shell from the frame. Notice the orientation of the light board inside so that you can install the decoder in the same orientation.
2. Carefully remove the plastic light shroud at the front of the loco and loosen the frame screws enough to allow the removal of the light board. Lift the board out of the frame.
3. Install the decoder, between the frame halves as shown. The narrow part of the decoder fits between the frame with the frame clips holding it at the corners of the decoder cutout. The brass motor contacts should contact the matching pads on the bottom of the decoder and be clear of the metal frame. Squeeze the frame halves together to hold the decoder in place.