Keeping with Jeff's consistent question - what plant? The San Jose assembly plant used a seat frame company located in the Los Angeles area and I've seen more paper tags on early (64-67) seats from them.
When I rebuild a seat I make it a point to reuse the tags with a new hog ring. I guess that's why I can't find any seat tags in the "tag heaven" container.
I do have a 3 3/4 X 1 7/8 paper tag with part number "C4ZB 6563810 A", "Quantity 100", "badge no 40", date "blank", from the "Young Spring & Wire Corp. Archbold, Ohio". The base number "63810" does not appear in either the illustrated or part number section so I assume that "63810" is a sub-component part of a seat, probably the frame. Ford service sold partially completed seats, frames were assembled. The tag is now a novelty. It exists but what it identifies is unknown.
Jim