In Japan D51/C61 etc... are meant to designate the series of the train, the designation has a meaning which I did once find on the internet, it relates to the size of the loco, number of driving wheels etc...
So in your example of the D51-200 what this means is it is the D51 class and was the 200th example manufacturered.
You will find in the Tomy range several different D51's which are mostly very similar but which have small differences as they replicate models of real life versions with the same number, the D51-200 being one of them.
I wasn't the person who customised those coaches with lights, but it can be done, typically you'd use LED's of some type, a battery and a switch either on the bottom or on one end depending on the type of coach/wagon and where the empty space is in them. For things like tail lights you'd need to drill some holes and fix some mini-LED's into the holes wiring up batteries/switch etc... inside it. Something that is fairly easy to someone used to that sort of thing, but not a task taken on by someone who is unfamiliar with a soldering iron, drill, etc...
As for the number of plarail steam trains? I really don't know how many have been made, but in the generic mass market versions I think there are 4 or 5 - I'm sure someone on here will have a list of them
In terms of specials there could be many, there are at least a couple of museum releases but also various starter sets including one that not only has a light but also a steam unit Although the latter is not cheap even second hand...
So in your example of the D51-200 what this means is it is the D51 class and was the 200th example manufacturered.
You will find in the Tomy range several different D51's which are mostly very similar but which have small differences as they replicate models of real life versions with the same number, the D51-200 being one of them.
I wasn't the person who customised those coaches with lights, but it can be done, typically you'd use LED's of some type, a battery and a switch either on the bottom or on one end depending on the type of coach/wagon and where the empty space is in them. For things like tail lights you'd need to drill some holes and fix some mini-LED's into the holes wiring up batteries/switch etc... inside it. Something that is fairly easy to someone used to that sort of thing, but not a task taken on by someone who is unfamiliar with a soldering iron, drill, etc...
As for the number of plarail steam trains? I really don't know how many have been made, but in the generic mass market versions I think there are 4 or 5 - I'm sure someone on here will have a list of them
In terms of specials there could be many, there are at least a couple of museum releases but also various starter sets including one that not only has a light but also a steam unit
Although the latter is not cheap even second hand...
Happily collecting things all my life... 
(This post was last modified: 08-17-2017, 12:13 AM by Super.)