Well, as I discussed (in another thread, I believe), one of the advantages to making product "in house" is that when you "run a mold" it is more cost effective to make more product than you will need AT THAT POINT and store the extras "on the shelf." (molding 1000 pieces is almost the same cost as molding 500; per piece cost though is almost one-half) Of course, this means you have to have shelves with space to store them (space is money), and you have to keep track of them too (that's not so hard nowadays with computers). This is what ACG did. One day the line might be making freight car trucks; well, you make "bunches" of them as the machinery and the people are 'jigged up" (politically incorrect term now) to do that job. Into the bins they go, so when tank cars, or flat cars or whatever are on the assembly line, the trucks are all ready to go on. This is just the opposite of JIT (Just In Time) production and inventorying used nowadays. But, for a long-term product line it can be more economical to do. It also allows one to respond to unexpected market demand. It is also why so much of ACG production used shared components.
This kind of thinking runs counter to "modern" production ideas, but, as we have seen here, it allows one to meet an unforeseen product demand. In this case, it is a win-win. We get cars to put behind a neat locomotive, Ron gets accolades for producing them AND income (I hope!), and uses up some inventory. Of course, the downside is that he will have to make more car body parts the next time he wants to create another passenger set. But on the upside, he probably gets some more loyal customers (Loyal customers, what an antiquated idea!).
Ron might say, "no big deal," but for "the other guys" who are locked into modern production overseas, it IS a big deal. For example, I am still waiting for my S-Fest Root Beer cars--I'm sure I'll get them, but it's a long wait! I'm told it is because of a miscommunications with the production manager in China. In Ron's case he just walks over to the production floor and says, "Hey, where are those cars??" (Actually, Ron is probably the production manager, so he just talks to himself--err, uh,. . Never mind. . . .)
Now Ron, about that Daylight 4-8-4. . . . .(you have the correct cars to run behind it!) 
