I don't have an instrument to measure the thickness of the card. But going through my near set, I found a few that seem a little thin:
#44 Chuck Weber
#103 Bob St. Clair
#186 Frank Youso
#193 Joe Krakoski
Also this one that feels thin for sure, and has the "gutter" that Footballdude mentions. So I would guess that this Bobby Layne card #126 was cut from the "Post-Ten Bottom Tray"?
Larry