Posted By:
Paul SNo apathy here. Just took me some time to get around to it, and I'm not sure that I'm representative to a thorough answer. Leon has successfully guilted me into fulfilling my forum obligation 
However, I just checked my 150 or so '60 Topps. None of them are missing the yellow on the back. I bought most of mine around the mid-late 1960s, meaning that I doubt the reason I have no missing-yellow cards wouldn't be because someone was specifically collecting them for scarcity. BTW, these were bought on the west coast.