[DaleM]

I don't think anyone has really come up with a valid explanation of the infamous "E" week. It's been offered that the first (A) week begins on the first Monday of a month and the work week was generally Mon-Fri. If the last days of a given month fall in the same Mon-Fri week as the first few days of the next month, they're considered the "E" week of the previous month.

Personally, I dont' buy it. I think it varies from plant to plant and each had their way of doing "A"..."E" weeks.

I track 66 & 67 Chevelle VINs and body tags and have found the following months and plants with "E" week tags:
1966 model year
Dec. (1965) - KC
Jan. (1966) - Fremont
Mar. (1966) - KC & Fremont
Apr. (1966) - Flint
May (1966) - Fremont
June (1966) - Atlanta & KC

1967 model year
Aug. (1966) - KC
Sep. (1966) - Atlanta, Baltimore, Fremont
Nov. (1966) - KC, Fremont
Jan. (1967) - KC
Mar. (1967) - Baltimore, Fremont
May (1967) - KC
June (1967) - Baltimore, Fremont

I'd bet other years and plants would show the same type trend.