Yearly production numbers question.

[White70C20]

Just out of curiosity I de-coded the VINs on both of my pickups and discovered that one was built at the St. Louis plant, and the other at the Fremont plant. The last 6 numbers of both VINs are only about 1,000 apart from each other. I was wondering if those 6 numbers only represent the number of vehicles built at that plant, or total production for 1970 over all the factories. If it is the latter, I think it's pretty cool that I have two trucks that were built that close in time to each other.