Installing a LE0511W into a Kato n-scale SD40-2
 
This is very straight forward.  There is plenty of room to fit the decoder beneath the rear of the light-board without any modifications to the frame, see the finished side view below.
1. Disassemble the engine by pulling off the body.  This is really quite easy, watch for the walkway catching on the light board's motor tabs.
2. Remove the light board, it will need to be modified.  The original looks like this:
Front
3. To wire the decoder, using the light-board, several of the traces need to be cut: to isolate the track power; the motor feed; and the lights.  The six cuts are indicated as red lines in the picture below.  I used a Dremel Tool to do this.  The configuration of the LEDs are such that the central trace can be used to feed the forward LED.  The common to both LEDs requires the Blue wire to attach to two places, see below.
Front
4. Install two 510 ohm resistors to drive the LEDs.  You may want to use slightly higher values.  I also pre-soldered in preparation for attaching the decoder wires.  Note again that the Blue wire attaches to two places.
Front
5. Cut the wires on the decoder as follows:
  •  White:     1.75 cm                                      0.7 in
  •  Yellow:    1.5 cm                                        0.6 in
  •  Orange:   4 cm                                           1.6 in
  •  Grey:       4.25 cm                                      1.7 in
  •  Blue:       6.25 cm, stripped at 1.5 cm        2.5, stripped at 0.6 in
  •  Black:     7.25 cm                                       2.9 in
  •  Red:       7.25 cm                                       2.9 in
Front
6. Solder the wires on.  I placed a thin piece of plastic under the decoder and added some electrician's tape to secure the decoder.
Front
7. The above picture shows the installed decoder.
Hints:
  • The copper pick-ups like to spring out, if you pick up the engine at the centre, they tend to stay put.
  • When taking off the shell, the walkway often gets stuck on the motor tabs on the light board, so push the tabs in to let the shell free.