I have Modified a few lionel carriages with sound systems purchased from ITT products West Hills CA
A very helpful guy, even adapted some of the basic sounds for me. I have modified the end of car by putting RED LEDs and a light bulb all power from the track and as the sound modules will also accept up to four LEDs I removed a couple of the bulbs and used the LEDs to simulate a power dimming effect. they look and sound good. if you need any more photos just ask.