[Keith Seymore]

Couple additional thoughts:

a) The "879984" is the sequential part of the VIN. Since it's a Chevy, I would guess that they started at 100001, so the sequence would be 879984 - 100001 = 779983, which would be pretty late in the model year. The fact that you made the purchase in July of '69 would seem to confirm this. Also, the VIN sequence number is specific to the plant; said differently, there is no correlation between VINs issued at different plants.

b) I'm not sure how many vehicles were made in St Louis. In my other life as a Pontiac hobbyist, I am aware of a book that has all the build dates, start and stop dates and production volumes. It is by John Gunnells and is called the "Standard Catalog of Pontiac, 1926 - 1995". You might check and see if such a book exists for '68 - '72 Chevy trucks. Edit: the author seems to indicate there is a book called the "Standard Catalog of American Light Duty Trucks, 1896 - 1986". Might be worth a shot.

FWIW -

K