I think those numbers are quality control or inspection. The last 6 numbers appear to be a European date. 300708 ---> July 30, 2008, 210808 ---> August 8, 2008.

I think your asking price is very fair. I'm just trying to figure out if I can get bottom matching covers at reasonable price. These would be nice to have for a future interior restoration. The covers appear to be symmetrical from what I can tell in pictures.