First post here so if this has been answered before I apologize and I'm not looking to decode a cowl tag but gather information on how the date is determined. I'm in a Chevelle thread at Team Chevelle discussing body dates on trim/cowl tags vs. the date appearing on the build sheet and I assume the same would apply to the Camaro. My questions concern the month/week date on a Fisher Body plate, a.k.a., trim or cowl tag and the flow of the paperwork. I know the date represents a month and week and have a specific question on how the 'week' is arrived at.
First, what physically constitutes a week of A, B, C, D, or E?
1. I initially thought it was the physical week of a month. If the 1st of the month started on a Wednesday, then Wednesday thru Saturday (1-4) were week A, 5-11, week B, etc. But, some months would have 6 'weeks' using this method.
2. My second thought is that week "A" are dates 1-7, week "B" are dates 8-14, up through week "E" dates of 29-31 where applicable regardless of the day of the week. Using this second method, every month except Feb (except a leap year) would have weeks A..E. It seems logical (therefore probably wrong) that the procedure for stamping the cowl tag would be simplified if a physical calendar was not required to convert a day's date into a week letter. These had to be automated and stamped by the hundreds so what logic, program or human, determined when the date should change from 01A to 01B? Whatever the logic involved this dating systems seems to hold true for the majority of cowl tag dates when compared to build sheet dates, but there are exceptions. One example I know of, on a 1970 Chevelle, has a cowl tag date of 01A but a build sheet date of 01-09.
Second, reading the excellent "Assembly Process" page the cowl tag was installed on the Fisher Body side fairly early during the body framing stage. The cowl tag obviously had not only the assembly date but other information that indicates (to me anyway) the car was locked into production even though a VIN hadn't been assigned yet by Chevrolet.
Can I assume the initial paperwork to build the car would come from Chevrolet and note what colors, options, etc. are to be used and the date on the build sheet would be the date the car is initiated? Assuming the body numbers and other groups of data from the build sheet are coded onto the cowl tag for tracking and when completed at Fisher and sent to Chevrolet for final assembly, the final sequence number (last 6 digits of the VIN) is then put on the build sheet; at least on Chevelles, this sequence number looks like it's stamped after the sheet was initially printed and in a different font and often at an angle in the upper right.
Question #2 is how does the date on the build sheet correlate to the body assembly date on the cowl tag? Using the 01A/01-09 example above, how would a car who's conception date of January 9, 1970 get a body assembly date of the first week (01A) of January? Assuming my theory of A=1-7, B=8-14, etc. I can see where a conception date of say 09-20 might get a "D" week (22-28) instead of a "C" week (15-21) coding if the car wasn't physically started for a day or two but not the other way around as in the case of the 01-09 car with an "A" week.
I guess the first thing to establish is how is the 'week' letter determined. Second is the relationship between the build sheet date and the beginning of the car's build cycle. Hopefully then the relationship between the two can be determined. I'm looking forward to the discussion, thank you.