Jimmy,
This is where the tiny surface mount device LEDs (SMD LED) really shines. Some really handy people wire them with leads, but they are so small it's easier to just buy them with leads attached. Yes, more expensive, but not a big deal for that special project.
There are other sources, but I use the Richmond Controls ones available from Ulrich: http://www.ulrichmodels.biz/miniature-surface-mount-leds-with-6-leads/
They also offer a selection of dicthlight housings (many also available elsewhere), if you want to do all your shopping in one place to avoid added shipping cost: http://www.ulrichmodels.biz/leds-and-led-lighting-kits/
You'll need some arrangement of wipers on the wheels (must be metal of course) to pick up juice from the rails. Or you could go with internal batteries, which have their own set of hassles.
From there is depends on whether you're DC or DCC. Don't forget a protective resistor in any case on your LEDs. There are several different useful circuits to provide easy flicker-free lighting. For a install like this, a switch or decoder to control the lighting on the back sems like a must. Since you're going to the trouble, why not light the interior of the car, too, as you'll have all the rest of the needed hardware already in place to serve the rear platform lights?
Mike Lehman
Urbana, IL
I'm starting to do a model or CSX theater car "Georiga". I'm planning to only do the window end interior, and part of the exterior is three light sets on the end- one like a headlight and two " ditch lights" on the opposite sides. they stay lit when it is being run, So my question is, how would one go about adding the functioning steady lights?
(My Model Railroad, My Rules)
These are the opinions of an under 35 , from the east end of, and modeling, the same section of the Wheeling and Lake Erie railway. As well as a freelanced road (Austinville and Dynamite City railroad).