I'd like to light a boxcar top

Well, the process shouldn't be too bad. First, just to be clear about what you want:

At one point, you mention a *blinking* light. If that's the case, Evan Designs has small pre-wired blinking LED lights that will accept full accessory or track voltage (AC or DC), so all you'd have to do is install the light where you want it, and connect the wires to the truck with the pickup roller. I used a red one at the top of my scratch-built cell tower (briefly seen about 25 seconds in):



OTOH, if you don't need the light to blink, there's lots of suppliers that offer inexpensive pre-wired LED or grain of wheat incandescent bulbs that run on accessory or track voltage, AC or DC. Again, all you'd need to do is just install and connect to the pickup rollers.

You also did not specify a color. Some pre-wired lights come in different colors, and there are transparent and translucent paints available to tint clear bulbs to the desired hue. Good luck!

Well, it's not clear in the pics (mostly because I decided against modeling them!), but the idea is that there are metal rungs to support the workmen's feet, backed up by the strap. The poor guy in the middle was adapted from a forestry crew set, so I took a few liberties with the mechanics. I doubt there are bucket trucks quite *that* high, though!

I second these. They have them in other colors as well.