Disagree. These are mass marketed and produced products. Production numbers needed to be known for all makes and models in order to budget and plan for marketing and manufacturing. It was just as necessary to know how many 2 door Imperials were sold as it was Superbirds.
Factory shipping reports and documentation exists for some lines, mostly B bodies. Regrettably, numbers are not known, or not released and published, for all lines.
I will completely agree that ALL things about producing a vehicle are known, with regards to planned installation rates and such, at the start of model year production. Just a normal situation of building anything. BUT, except as mentioned, much of this was discarded a few years afterward, for the particular model year. Reason for that? File space was needed. Much of it went to the dumpster whenever it was necessary to be disposed of. This happened at ALL of the OEMs, not just Chrysler.
In the '60s and prior, production figures were not usually something people thought about. Unless it was a specific model or some other "race car homologation" issue. As the general economy improved, so did the installation rates of "luxury" items as power seats, power windows, cruise controls, etc. It was generally of concern as to how many Street Hemi cars were built, in which model, etc. AND how to correctly identify a "HEMI car" from a normal car on the same platform. Then came 4-speeds and TFs. Track Pak, Super Track Pak, etc. These were B/E-body cars, usually, which probably expanded things to ALL option/trim combinations for the famous "1 of ___" combinations.
In general, once the vendor bills had been paid, everybody was happy, the transportation expenses had been paid, just like any other "old bills", those files were purged as a matter of course. Any perceived "historical value" was nil, especially for the non-performance general vehicles. Unfortunately, that would probably include C-body cars, generally.
Now, there was a gentleman who had run Chrysler Historical and moved all of those "file cabinets" off-site to prevent the historical files from being destroyed, in the 1980s as Chrysler's financial situation deteriorated, THEN. I think that he and an assistant comprised the whole Chrysler Historical operation, back then?
After the earlier financial crisis was over, he moved the files back on-site and a new Chrysler Historical operation was configured. Bigger than before AND celebrated, rather then otherwise. After these accomplishments, he later retired. I believe he passed away several years ago.
In the mean time, several specific "registries" have come online. I also suspect that IF more specific production figures had been available, the Standard Book of Chrysler probably would have included them?
In the case of Buick, when it was noticed that these "purges for file space" were going on, many people emptied the dumpsters themselves, before the trash company arrived. Some was lost before they knew this was going on, but much was saved and archived. Each GM division had their own orientation on these things, with Pontiac being the first to let people know they had "items", other than the Corvette operatives.
In cases where "collectability" increased well after the particular model year of vehicles had been produced, it's a little difficult to go back and dig up the production rate information. MUCH moreso as much of that information was destroyed, years prior. Whether particular items were purged or archived might have also depended upon whom was making those decisions, back then. If a particular carline manager could have either decided to "put that stuff somewhere else, where it's safe" or "get rid of it", which can explain why some files still exist and others don't.
For many, "cars are just metal", whereas for others "cars are art", or "cars can be future collectibles, so keeping informion can be advisable".
Not to sound flaky, but just be glad that what we now have WAS saved by people with a vision to what future generations might need for various hobby activities. That many who saved items, back then, have shared them with us in varied ways/registries, etc. When the cars were built, some 40+ years ago, it was a different world, cars included. People generally bought the cars to enjoy, use, and replace in a few years. Few were bought and "put away", as some more recent ones were. Those that were, eventually were sold at auctions. Unfortunately, in the case of some Pace Car or __th Anniversary Edition Corvettes, their eventual selling price was not a very good long-term investment, especially the Silver Anniversary Editions (in particular).
IF anybody HAD every suspected the current following that C-body Chrysler products now have, back then, perhaps things might be different. I'll not speculate that all of the available information has been found, either.
Just some thoughts,
CBODY67