Here is the question, what exactly would be the documentation needed to show the correct day the car rolled off the line, and would that documentation actually exist for any car?
Paper documents like window stickers, shipping and sales paperwork, including Advance Dealer Shipping notices, broadcast sheets, and door stickers always help. As with anything else, patterns emerge when you compare data.
One line of ongoing research: It appears that St. Louis Plant broadcast sheets carry a different print date when compared to the SPD. This variation in date, if the theory holds, seems to give a more precise plus or minus assembly date to the SPD. As plants number sheets differently, this concept may or may not hold true with the Jefferson, Belvdiere or Newark C body plants. One needs to collect and review sheets to see what they tell us.
Some plants (Hamtramck) number sheets sequentially meaning you can place relative order of production for the car regardless of the SPD. With Lynch Road cars you can use the body in white sequence number to help with same concept.
Researching and documenting dated coded parts always helps. One indicator of a more precise assembly date for 69 Lynch Road cars seems to be K frames. Does this hold true with C bodies? Maybe. It could be checked.
It could be done but I think documenting C bodies to get the desired information will/would be incredibly difficult compared to B and E bodies.
1) lower initial production numbers meaning lower possible data points 2) lower percentage and number of surviving cars to document 3) lack of credible current industry research available (no widespread documentation like the Options and Accessories reports in the market. IF the same shipping data exists for C bodies as it does for A,B and C bodies, it needs to be put into a similar format as to what GG uses and disiminated) 4) Apparent lack of ongoing research and sharing of results. Para Fuega (sp?) is doing some excellent and necessary documentation and research on the last C bodies. 5) Lack of concern or care for the above topics.
People have to care about the topic first before anything can or will be done. Someone needs to actively seek out and compile broadcast and window sticker information in C bodies. Someone needs to collaborate with others in the hobby to share info. Someone needs to look at the comparisons between the information and SPDs to see how each year and plant is similar and different.
Does accurate information matter? To some but not all.